Data Analysis Workshop

Linking health survey data with climate datasets in R

Matt Gunther - Senior Data Analyst

Devon Kristiansen - Project Manager

Data and Research Question

IPUMS PMA: Fertility outcomes for women in Burkina Faso

Toy GPS data: coordinates for each PMA sample cluster

CHIRPS: Rainfall accumulation relative to local averages

Do rainfall conditions influence women’s short-term family planning decisions?

Setup

Follow these steps to obtain today’s code & publicly available data.

Open analysis.rmd and begin following along with these code chunks

# IPUMS & Spatial Data Tools
library(tidyverse)
library(ipumsr) 
library(sf)
library(terra)
library(ggspatial)

# Analysis Tools 
library(srvyr)
library(survey)
library(lme4)
library(broom)
library(broom.mixed)

1 - IPUMS PMA Data

Downloading IPUMS PMA data

Visit the IPUMS PMA data website

Sample
- Burkina Faso
- Longitudinal
- Female Respondents Only
Variables
- RESULTFQ
- PANELBIRTH
- PANELWEIGHT
- EAID
- URBAN

Load IPUMS PMA data into R

You’ll receive two files from IPUMS - put both in the data folder where analysis.Rmd is located.

pma <- read_ipums_micro(
  ddi = "data/pma_00136.xml", # Use your own file name here 
  data = "data/pma_00136.dat.gz" # Use your own file name here 
)

# A tibble: 8,257 × 180
      SAMPLE_1    SAMPLE_2 SAMPLE_3 SAMPLE_4 COUNTRY YEAR_1 YEAR_2 YEAR_3 YEAR_4
     <int+lbl>   <int+lbl> <int+lb> <int+lb> <int+l>  <int>  <int>  <int>  <int>
 1 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 2 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 3 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 4 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 5 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 6 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 7 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 8 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
 9 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
10 85409 [Bur… 85412 [Bur…       NA       NA 1 [Bur…   2019   2021     NA     NA
# … with 8,247 more rows, and 171 more variables: ELIGIBLE_1 <int+lbl>,
#   ELIGIBLE_2 <int+lbl>, EAID_1 <dbl>, EAID_2 <dbl>, EAID_3 <dbl>,
#   EAID_4 <dbl>, CONSENTFQ_1 <int+lbl>, CONSENTFQ_2 <int+lbl>,
#   RESULTFQ_1 <int+lbl>, RESULTFQ_2 <int+lbl>, CROSS_SECTION_1 <int+lbl>,
#   CROSS_SECTION_2 <int+lbl>, INTFQMON_1 <int+lbl>, INTFQMON_2 <int+lbl>,
#   INTFQYEAR_1 <int+lbl>, INTFQYEAR_2 <int+lbl>, FQINSTID <chr>,
#   CONSENTHQ_1 <int+lbl>, CONSENTHQ_2 <int+lbl>, FQWEIGHT_1 <dbl>, …

Data format

We’ve selected wide format longitudinal data, so Phase 1 and Phase 2 data are stored in separate columns.

pma %>% count(RESULTFQ_1, RESULTFQ_2)

# A tibble: 15 × 3
              RESULTFQ_1                                     RESULTFQ_2     n
               <int+lbl>                                      <int+lbl> <int>
 1  1 [Completed]         1 [Completed]                                  5487
 2  1 [Completed]         2 [Not at home]                                  78
 3  1 [Completed]         3 [Postponed]                                    22
 4  1 [Completed]         4 [Refused]                                      66
 5  1 [Completed]         5 [Partly completed]                             12
 6  1 [Completed]         7 [Respondent moved]                             15
 7  1 [Completed]        10 [Incapacitated]                                19
 8  1 [Completed]        95 [Not interviewed (female questionnaire)]        4
 9  1 [Completed]        96 [Not interviewed (household questionnaire)]   192
10  1 [Completed]        99 [NIU (not in universe)]                       399
11  1 [Completed]        NA                                               471
12  5 [Partly completed]  1 [Completed]                                     4
13  5 [Partly completed] NA                                                21
14 NA                     1 [Completed]                                  1460
15 NA                     5 [Partly completed]                              7

Keep only women who completed the survey in both phases of the panel study.

# Keep only panel members from both phases 
pma <- pma %>% filter(RESULTFQ_1 == 1 & RESULTFQ_2 == 1)

Questions about IPUMS PMA data?

2- PMA GPS data

About PMA GPS data

PMA uses spatially referenced sample clusters - called “enumeration areas” (EAs) - sampled by probability proportional to population size.

At the beginning of the panel study, 35 households were randomly selected within each EA.

About PMA GPS data

PMA uses spatially referenced sample clusters - called “enumeration areas” (EAs) - sampled by probability proportional to population size.

At the beginning of the panel study, 35 households were randomly selected within each EA.

IPUMS PMA does not disseminate the GPS coordinates for EAs, but you may apply here for access directly from PMA.

Today, we’ll be using falsified GPS coordinates as an example.

About PMA GPS data

PMA uses spatially referenced sample clusters - called “enumeration areas” (EAs) - sampled by probability proportional to population size.

At the beginning of the panel study, 35 households were randomly selected within each EA.

IPUMS PMA does not disseminate the GPS coordinates for EAs, but you may apply here for access directly from PMA.

Today, we’ll be using falsified GPS coordinates as an example.

About PMA GPS data

PMA uses spatially referenced sample clusters - called “enumeration areas” (EAs) - sampled by probability proportional to population size.

At the beginning of the panel study, 35 households were randomly selected within each EA.

IPUMS PMA does not disseminate the GPS coordinates for EAs, but you may apply here for access directly from PMA.

Today, we’ll be using falsified GPS coordinates as an example.

The coordinates represent the centroid of an enumeration area, not the location of any sampled household.

Load PMA GPS data into R

A PMA GPS dataset is a simple CSV file with one row per EA, and columns containing latitude and longitude points.

gps <- read_csv("data/pma_gps.csv")

# A tibble: 167 × 8
   PMACC PMAYEAR REGION                EAID GPSLONG GPSLAT DATUM SURVEY
   <chr>   <dbl> <chr>                <dbl>   <dbl>  <dbl> <chr> <chr> 
 1 BF       2020 8. est           854181006 -0.160    13.4 WGS84 PMA   
 2 BF       2020 3. centre        854131035 -1.47     12.4 WGS84 PMA   
 3 BF       2020 6. centre_ouest  854161005 -1.92     11.1 WGS84 PMA   
 4 BF       2020 10. nord         854201013 -2.54     12.9 WGS84 PMA   
 5 BF       2020 9. hauts_bassins 854191041 -4.23     11.2 WGS84 PMA   
 6 BF       2020 2. cascades      854121002 -4.84     10.3 WGS84 PMA   
 7 BF       2020 6. centre_ouest  854161009 -2.20     12.8 WGS84 PMA   
 8 BF       2020 8. est           854181005 -0.0319   12.5 WGS84 PMA   
 9 BF       2020 10. nord         854201005 -1.90     12.9 WGS84 PMA   
10 BF       2020 9. hauts_bassins 854191026 -5.24     11.4 WGS84 PMA   
# … with 157 more rows

The column DATUM describes the coordinate reference system: World Geodetic System 1984.

GPS data as a Simple Features Object

The sf (“simple features”) package for R contains many of the same tools you would find in other GIS software

gps <- gps %>% 
  st_as_sf(
    coords = c("GPSLONG", "GPSLAT"), 
    crs = 4326
  )

GPS data as a Simple Features Object

The sf (“simple features”) package for R contains many of the same tools you would find in other GIS software

gps <- gps %>% 
  st_as_sf(
    coords = c("GPSLONG", "GPSLAT"), 
    crs = 4326
  )

4326 is the EPSG code for World Geodetic System 1984.

Simple feature collection with 167 features and 6 fields
Geometry type: POINT
Dimension:     XY
Bounding box:  xmin: -5.277929 ymin: 10.29263 xmax: 0.6744602 ymax: 14.21399
Geodetic CRS:  WGS 84
# A tibble: 167 × 7
   PMACC PMAYEAR REGION              EAID DATUM SURVEY               geometry
 * <chr>   <dbl> <chr>              <dbl> <chr> <chr>             <POINT [°]>
 1 BF       2020 8. est            8.54e8 WGS84 PMA     (-0.1595212 13.36634)
 2 BF       2020 3. centre         8.54e8 WGS84 PMA      (-1.467466 12.43239)
 3 BF       2020 6. centre_ouest   8.54e8 WGS84 PMA      (-1.915129 11.13271)
 4 BF       2020 10. nord          8.54e8 WGS84 PMA      (-2.542757 12.88571)
 5 BF       2020 9. hauts_bassins  8.54e8 WGS84 PMA      (-4.232418 11.19971)
 6 BF       2020 2. cascades       8.54e8 WGS84 PMA       (-4.83967 10.29263)
 7 BF       2020 6. centre_ouest   8.54e8 WGS84 PMA      (-2.204062 12.75554)
 8 BF       2020 8. est            8.54e8 WGS84 PMA    (-0.03191096 12.45061)
 9 BF       2020 10. nord          8.54e8 WGS84 PMA      (-1.895065 12.90935)
10 BF       2020 9. hauts_bassins  8.54e8 WGS84 PMA      (-5.239322 11.37056)
# … with 157 more rows

Adding a Shapefile

We need a supplementary shape file to see where each point lies on a map of Burkina Faso.

You only need to specify the folder: R will locate the appropriate file.

shape <- st_read("data/geobf") %>% select(ADMIN_NAME)

Simple feature collection with 13 features and 1 field
Geometry type: MULTIPOLYGON
Dimension:     XY
Bounding box:  xmin: -5.521112 ymin: 9.393889 xmax: 2.404293 ymax: 15.08511
Geodetic CRS:  WGS 84
First 10 features:
          ADMIN_NAME                       geometry
1  Boucle du Mouhoun MULTIPOLYGON (((-3.206306 1...
2           Cascades MULTIPOLYGON (((-5.388849 1...
3             Centre MULTIPOLYGON (((-1.565052 1...
4         Centre-Est MULTIPOLYGON (((-0.2517975 ...
5        Centre-Nord MULTIPOLYGON (((-0.6722373 ...
6       Centre-Ouest MULTIPOLYGON (((-2.547486 1...
7         Centre-Sud MULTIPOLYGON (((-1.470801 1...
8                Est MULTIPOLYGON (((0.06834642 ...
9      Hauts-Bassins MULTIPOLYGON (((-4.483203 1...
10              Nord MULTIPOLYGON (((-2.952616 1...

Mapping GPS coordinates

ggplot() + 
  layer_spatial(gps) + 
  theme_minimal()

Mapping GPS coordinates

ggplot() + 
  layer_spatial(gps) + 
  layer_spatial(shape, alpha = 0) + 
  theme_minimal()

PMA displacement protocol

In fact, these GPS coordinates are not the actual centroid of each EA.

In order to preserve confidentiality, PMA displaces the centroid location of each EA up to 2 km (urban areas) or 5 km (rural areas).

Displacement does not cross admin 1 boundaries.

Meters on a Round Plant

Remember: the geometry of our gps data is defined by arc-degrees, not meters.

If we tried to account displacement in meters without “flattening” our map, the length of one meter vary based on distance from the equator.

Projection to Meters

We’ll use EPSG code 32630 to focus our flat projection around Burkina Faso.

gps <- gps %>% st_transform(crs = 32630)
shape <- shape %>% st_transform(crs = 32630)

Simple feature collection with 167 features and 6 fields
Geometry type: POINT
Dimension:     XY
Bounding box:  xmin: 250808.3 ymin: 1138345 xmax: 899207.2 ymax: 1573191
Projected CRS: WGS 84 / UTM zone 30N
# A tibble: 167 × 7
   PMACC PMAYEAR REGION              EAID DATUM SURVEY           geometry
 * <chr>   <dbl> <chr>              <dbl> <chr> <chr>         <POINT [m]>
 1 BF       2020 8. est            8.54e8 WGS84 PMA    (807680.7 1479413)
 2 BF       2020 3. centre         8.54e8 WGS84 PMA    (666577.8 1374847)
 3 BF       2020 6. centre_ouest   8.54e8 WGS84 PMA    (618468.7 1230870)
 4 BF       2020 10. nord          8.54e8 WGS84 PMA    (549607.1 1424541)
 5 BF       2020 9. hauts_bassins  8.54e8 WGS84 PMA    (365447.7 1238343)
 6 BF       2020 2. cascades       8.54e8 WGS84 PMA    (298530.9 1138345)
 7 BF       2020 6. centre_ouest   8.54e8 WGS84 PMA    (586398.8 1410234)
 8 BF       2020 8. est            8.54e8 WGS84 PMA    (822688.7 1378185)
 9 BF       2020 10. nord          8.54e8 WGS84 PMA    (619870.7 1427369)
10 BF       2020 9. hauts_bassins  8.54e8 WGS84 PMA    (255620.7 1257895)
# … with 157 more rows

This changes the geometry column to meters [m].

Creating Buffers

To keep things simple in our example, we’ll give every EA a 5 km buffer.

gps_buffer <- gps %>% st_buffer(5000)

Simple feature collection with 167 features and 6 fields
Geometry type: POLYGON
Dimension:     XY
Bounding box:  xmin: 245808.3 ymin: 1133345 xmax: 904207.2 ymax: 1578191
Projected CRS: WGS 84 / UTM zone 30N
# A tibble: 167 × 7
   PMACC PMAYEAR REGION              EAID DATUM SURVEY                  geometry
 * <chr>   <dbl> <chr>              <dbl> <chr> <chr>              <POLYGON [m]>
 1 BF       2020 8. est            8.54e8 WGS84 PMA    ((812680.7 1479413, 8126…
 2 BF       2020 3. centre         8.54e8 WGS84 PMA    ((671577.8 1374847, 6715…
 3 BF       2020 6. centre_ouest   8.54e8 WGS84 PMA    ((623468.7 1230870, 6234…
 4 BF       2020 10. nord          8.54e8 WGS84 PMA    ((554607.1 1424541, 5546…
 5 BF       2020 9. hauts_bassins  8.54e8 WGS84 PMA    ((370447.7 1238343, 3704…
 6 BF       2020 2. cascades       8.54e8 WGS84 PMA    ((303530.9 1138345, 3035…
 7 BF       2020 6. centre_ouest   8.54e8 WGS84 PMA    ((591398.8 1410234, 5913…
 8 BF       2020 8. est            8.54e8 WGS84 PMA    ((827688.7 1378185, 8276…
 9 BF       2020 10. nord          8.54e8 WGS84 PMA    ((624870.7 1427369, 6248…
10 BF       2020 9. hauts_bassins  8.54e8 WGS84 PMA    ((260620.7 1257895, 2606…
# … with 157 more rows

Now, geometry contains several points on the circumference of a round polygon.

Intersecting Regional Boundaries

In certain cases, a buffer may cross an admin 1 boundary in shape.

For example, we’ll look at enumeration area 854131009

test_ea <- 854131009

Intersecting Regional Boundaries

In certain cases, a buffer may cross an admin 1 boundary in shape.

For example, we’ll look at enumeration area 854131009

test_ea <- 854131009

Keep only the segment containing the original centroid.

gps_buffer <- gps_buffer %>% 
  st_intersection(shape) %>% 
  st_filter(gps)

Intersecting Regional Boundaries

In certain cases, a buffer may cross an admin 1 boundary in shape.

For example, we’ll look at enumeration area 854131009

test_ea <- 854131009

Keep only the segment containing the original centroid.

gps_buffer <- gps_buffer %>% 
  st_intersection(shape) %>% 
  st_filter(gps)

Back to arc-degrees

Finally, we can return to our original CRS defined by arc-degrees.

gps_buffer <- gps_buffer %>% st_transform(crs = 4326)
shape <- shape %>% st_transform(crs = 4326)

ggplot() + 
  layer_spatial(shape, alpha = 0) + 
  layer_spatial(gps_buffer, alpha = 0) + 
  theme_minimal()

Questions about PMA GPS Data?

3 - Mapping Birth Outcomes

Birth outcomes for individuals

Now, we combine pma together with gps_buffer.

The pma variable PANELBIRTH_2 indicates whether each woman gave birth within the year that passed between Phase 1 and Phase 2 of the panel study.

pma %>% count(PANELBIRTH_2)

# A tibble: 3 × 2
                PANELBIRTH_2     n
                   <int+lbl> <int>
1  0 [No]                     3412
2  1 [Yes]                     772
3 99 [NIU (not in universe)]  1303

Important: Code 99 represents women who were “not in universe” because they had indicated elsewhere on the survey that they had never given birth.

We can treat these cases as “No”.

pma %>% count(PANELBIRTH_2 == 1)

# A tibble: 2 × 2
  `PANELBIRTH_2 == 1`     n
  <lgl>               <int>
1 FALSE                4715
2 TRUE                  772

Birth outcomes by EA

Births above and below the median enumeration area:

ea_summary <- pma %>% 
  as_survey_design(weight = PANELWEIGHT) %>% 
  group_by(ea = EAID_1, urban = URBAN == 1) %>% 
  summarise(birth_prop = survey_mean(PANELBIRTH_2 == 1, vartype = NULL)) %>% 
  ungroup()

# A tibble: 167 × 3
          ea urban birth_prop
       <dbl> <lgl>      <dbl>
 1 854111001 FALSE     0.228 
 2 854111002 TRUE      0.0469
 3 854111003 TRUE      0.190 
 4 854111004 FALSE     0.260 
 5 854111005 FALSE     0.304 
 6 854111006 TRUE      0.107 
 7 854111007 FALSE     0.218 
 8 854111008 FALSE     0.209 
 9 854111009 FALSE     0.118 
10 854111010 TRUE      0.148 
# … with 157 more rows

Birth outcomes by EA

Births above and below the median enumeration area:

ea_summary <- pma %>% 
  as_survey_design(weight = PANELWEIGHT) %>% 
  group_by(ea = EAID_1, urban = URBAN == 1) %>% 
  summarise(birth_prop = survey_mean(PANELBIRTH_2 == 1, vartype = NULL)) %>% 
  ungroup() %>% 
  mutate(
    ntile = ntile(birth_prop, 2)
  )

# A tibble: 167 × 4
          ea urban birth_prop ntile
       <dbl> <lgl>      <dbl> <int>
 1 854111001 FALSE     0.228      2
 2 854111002 TRUE      0.0469     1
 3 854111003 TRUE      0.190      2
 4 854111004 FALSE     0.260      2
 5 854111005 FALSE     0.304      2
 6 854111006 TRUE      0.107      1
 7 854111007 FALSE     0.218      2
 8 854111008 FALSE     0.209      2
 9 854111009 FALSE     0.118      1
10 854111010 TRUE      0.148      2
# … with 157 more rows

Birth outcomes by EA

Births above and below the median enumeration area:

ea_summary <- pma %>% 
  as_survey_design(weight = PANELWEIGHT) %>% 
  group_by(ea = EAID_1, urban = URBAN == 1) %>% 
  summarise(birth_prop = survey_mean(PANELBIRTH_2 == 1, vartype = NULL)) %>% 
  ungroup() %>% 
  mutate(
    ntile = ntile(birth_prop, 2),
    many_births = ntile == 2
  )

# A tibble: 167 × 5
          ea urban birth_prop ntile many_births
       <dbl> <lgl>      <dbl> <int> <lgl>      
 1 854111001 FALSE     0.228      2 TRUE       
 2 854111002 TRUE      0.0469     1 FALSE      
 3 854111003 TRUE      0.190      2 TRUE       
 4 854111004 FALSE     0.260      2 TRUE       
 5 854111005 FALSE     0.304      2 TRUE       
 6 854111006 TRUE      0.107      1 FALSE      
 7 854111007 FALSE     0.218      2 TRUE       
 8 854111008 FALSE     0.209      2 TRUE       
 9 854111009 FALSE     0.118      1 FALSE      
10 854111010 TRUE      0.148      2 TRUE       
# … with 157 more rows

Merging GPS data

Use full_join to merge all rows of ea_summary to gps_buffer.

If you list gps_buffer first, the result will be another Simple Features object.

ea_summary_gps <- full_join(
  gps_buffer %>% select(ea = EAID), 
  ea_summary, 
  by = "ea"
)

Simple feature collection with 167 features and 5 fields
Geometry type: POLYGON
Dimension:     XY
Bounding box:  xmin: -5.32361 ymin: 10.24743 xmax: 0.7204144 ymax: 14.25915
Geodetic CRS:  WGS 84
# A tibble: 167 × 6
          ea urban birth_prop ntile many_births                         geometry
       <dbl> <lgl>      <dbl> <int> <lgl>                          <POLYGON [°]>
 1 854111012 TRUE      0.253      2 TRUE        ((-3.856566 11.95614, -3.856747…
 2 854111006 TRUE      0.107      1 FALSE       ((-3.02159 11.87068, -3.021778 …
 3 854111002 TRUE      0.0469     1 FALSE       ((-3.202698 12.88706, -3.202886…
 4 854111007 FALSE     0.218      2 TRUE        ((-2.790317 12.89155, -2.790508…
 5 854111011 FALSE     0.150      2 TRUE        ((-3.474768 12.52022, -3.474953…
 6 854111008 FALSE     0.209      2 TRUE        ((-3.864223 13.27047, -3.864404…
 7 854191039 TRUE      0.196      2 TRUE        ((-3.235588 11.51495, -3.235775…
 8 854111003 TRUE      0.190      2 TRUE        ((-3.322203 12.54741, -3.322389…
 9 854191008 FALSE     0.190      2 TRUE        ((-4.30137 11.91649, -4.301547 …
10 854111010 TRUE      0.148      2 TRUE        ((-3.205145 12.61123, -3.205333…
# … with 157 more rows

Mapping Birth Outcomes by EA

ggplot() + 
  layer_spatial(ea_summary_gps, aes(fill = many_births)) + 
  layer_spatial(shape, alpha = 0) + 
  theme_minimal()

Questions about mapping?

4 - CHIRPS: Annual rainfall summary

Downloading CHIRPS data

Download a CHRIPS data extract from ClimateSERV

What is a Raster File?

When you open your download, you’ll find one file per day in our selected space and time period.

The .tif file format is a high-resolution image.

For CHRIPS, each pixel represents mm rainfall in an area 0.05 degrees longitude by 0.05 degrees latitude.

Load Raster Data into R

The terra package reads Raster files.

You could simply read the data from a single day, and map the result.

june5_2020 <- rast("data/chirps/20200605.tif")

class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : 20200605.tif 
name        : 20200605

This output summaries the .tif file for June 5, 2020. Notice that there are:

115 rows of pixels
159 columns of pixels
1 layer named 20211028

June 5, 2020

ggplot() + 
  layer_spatial(june5_2020) + 
  layer_spatial(shape, alpha = 0) + 
  theme_minimal()

June 5, 2020

ggplot() + 
  layer_spatial(june5_2020) + 
  layer_spatial(shape, alpha = 0) + 
  theme_minimal()

June 5, 2020

ggplot() + 
  layer_spatial(mask(june5_2020, vect(shape), touches = FALSE)) + 
  layer_spatial(shape, alpha = 0) + 
  theme_minimal()

June 5, 2020

ggplot() + 
  layer_spatial(mask(june5_2020, vect(shape), touches = FALSE)) + 
  layer_spatial(shape, alpha = 0) + 
  theme_minimal() + 
  scale_fill_gradient2(low = "transparent", high = "#4375B7", na.value = "transparent") + 
  labs(fill = "Rainfall (mm)")

Aggregation

Ultimately, you’ll want to work with .tif images from many days at the same time.

For this workshop, I’ve removed all files outside of the range June 1 to Oct 1.

years <- map(2001:2020, ~{
  list.files("data/chirps/", pattern = paste0("^", .x), full.names = TRUE)
})

years <- set_names(years, 2001:2020)

$`2001`
  [1] "data/chirps//20010601.tif" "data/chirps//20010602.tif"
  [3] "data/chirps//20010603.tif" "data/chirps//20010604.tif"
  [5] "data/chirps//20010605.tif" "data/chirps//20010606.tif"
  [7] "data/chirps//20010607.tif" "data/chirps//20010608.tif"
  [9] "data/chirps//20010609.tif" "data/chirps//20010610.tif"
 [11] "data/chirps//20010611.tif" "data/chirps//20010612.tif"
 [13] "data/chirps//20010613.tif" "data/chirps//20010614.tif"
 [15] "data/chirps//20010615.tif" "data/chirps//20010616.tif"
 [17] "data/chirps//20010617.tif" "data/chirps//20010618.tif"
 [19] "data/chirps//20010619.tif" "data/chirps//20010620.tif"
 [21] "data/chirps//20010621.tif" "data/chirps//20010622.tif"
 [23] "data/chirps//20010623.tif" "data/chirps//20010624.tif"
 [25] "data/chirps//20010625.tif" "data/chirps//20010626.tif"
 [27] "data/chirps//20010627.tif" "data/chirps//20010628.tif"
 [29] "data/chirps//20010629.tif" "data/chirps//20010630.tif"
 [31] "data/chirps//20010701.tif" "data/chirps//20010702.tif"
 [33] "data/chirps//20010703.tif" "data/chirps//20010704.tif"
 [35] "data/chirps//20010705.tif" "data/chirps//20010706.tif"
 [37] "data/chirps//20010707.tif" "data/chirps//20010708.tif"
 [39] "data/chirps//20010709.tif" "data/chirps//20010710.tif"
 [41] "data/chirps//20010711.tif" "data/chirps//20010712.tif"
 [43] "data/chirps//20010713.tif" "data/chirps//20010714.tif"
 [45] "data/chirps//20010715.tif" "data/chirps//20010716.tif"
 [47] "data/chirps//20010717.tif" "data/chirps//20010718.tif"
 [49] "data/chirps//20010719.tif" "data/chirps//20010720.tif"
 [51] "data/chirps//20010721.tif" "data/chirps//20010722.tif"
 [53] "data/chirps//20010723.tif" "data/chirps//20010724.tif"
 [55] "data/chirps//20010725.tif" "data/chirps//20010726.tif"
 [57] "data/chirps//20010727.tif" "data/chirps//20010728.tif"
 [59] "data/chirps//20010729.tif" "data/chirps//20010730.tif"
 [61] "data/chirps//20010731.tif" "data/chirps//20010801.tif"
 [63] "data/chirps//20010802.tif" "data/chirps//20010803.tif"
 [65] "data/chirps//20010804.tif" "data/chirps//20010805.tif"
 [67] "data/chirps//20010806.tif" "data/chirps//20010807.tif"
 [69] "data/chirps//20010808.tif" "data/chirps//20010809.tif"
 [71] "data/chirps//20010810.tif" "data/chirps//20010811.tif"
 [73] "data/chirps//20010812.tif" "data/chirps//20010813.tif"
 [75] "data/chirps//20010814.tif" "data/chirps//20010815.tif"
 [77] "data/chirps//20010816.tif" "data/chirps//20010817.tif"
 [79] "data/chirps//20010818.tif" "data/chirps//20010819.tif"
 [81] "data/chirps//20010820.tif" "data/chirps//20010821.tif"
 [83] "data/chirps//20010822.tif" "data/chirps//20010823.tif"
 [85] "data/chirps//20010824.tif" "data/chirps//20010825.tif"
 [87] "data/chirps//20010826.tif" "data/chirps//20010827.tif"
 [89] "data/chirps//20010828.tif" "data/chirps//20010829.tif"
 [91] "data/chirps//20010830.tif" "data/chirps//20010831.tif"
 [93] "data/chirps//20010901.tif" "data/chirps//20010902.tif"
 [95] "data/chirps//20010903.tif" "data/chirps//20010904.tif"
 [97] "data/chirps//20010905.tif" "data/chirps//20010906.tif"
 [99] "data/chirps//20010907.tif" "data/chirps//20010908.tif"
[101] "data/chirps//20010909.tif" "data/chirps//20010910.tif"
[103] "data/chirps//20010911.tif" "data/chirps//20010912.tif"
[105] "data/chirps//20010913.tif" "data/chirps//20010914.tif"
[107] "data/chirps//20010915.tif" "data/chirps//20010916.tif"
[109] "data/chirps//20010917.tif" "data/chirps//20010918.tif"
[111] "data/chirps//20010919.tif" "data/chirps//20010920.tif"
[113] "data/chirps//20010921.tif" "data/chirps//20010922.tif"
[115] "data/chirps//20010923.tif" "data/chirps//20010924.tif"
[117] "data/chirps//20010925.tif" "data/chirps//20010926.tif"
[119] "data/chirps//20010927.tif" "data/chirps//20010928.tif"
[121] "data/chirps//20010929.tif" "data/chirps//20010930.tif"

$`2002`
  [1] "data/chirps//20020601.tif" "data/chirps//20020602.tif"
  [3] "data/chirps//20020603.tif" "data/chirps//20020604.tif"
  [5] "data/chirps//20020605.tif" "data/chirps//20020606.tif"
  [7] "data/chirps//20020607.tif" "data/chirps//20020608.tif"
  [9] "data/chirps//20020609.tif" "data/chirps//20020610.tif"
 [11] "data/chirps//20020611.tif" "data/chirps//20020612.tif"
 [13] "data/chirps//20020613.tif" "data/chirps//20020614.tif"
 [15] "data/chirps//20020615.tif" "data/chirps//20020616.tif"
 [17] "data/chirps//20020617.tif" "data/chirps//20020618.tif"
 [19] "data/chirps//20020619.tif" "data/chirps//20020620.tif"
 [21] "data/chirps//20020621.tif" "data/chirps//20020622.tif"
 [23] "data/chirps//20020623.tif" "data/chirps//20020624.tif"
 [25] "data/chirps//20020625.tif" "data/chirps//20020626.tif"
 [27] "data/chirps//20020627.tif" "data/chirps//20020628.tif"
 [29] "data/chirps//20020629.tif" "data/chirps//20020630.tif"
 [31] "data/chirps//20020701.tif" "data/chirps//20020702.tif"
 [33] "data/chirps//20020703.tif" "data/chirps//20020704.tif"
 [35] "data/chirps//20020705.tif" "data/chirps//20020706.tif"
 [37] "data/chirps//20020707.tif" "data/chirps//20020708.tif"
 [39] "data/chirps//20020709.tif" "data/chirps//20020710.tif"
 [41] "data/chirps//20020711.tif" "data/chirps//20020712.tif"
 [43] "data/chirps//20020713.tif" "data/chirps//20020714.tif"
 [45] "data/chirps//20020715.tif" "data/chirps//20020716.tif"
 [47] "data/chirps//20020717.tif" "data/chirps//20020718.tif"
 [49] "data/chirps//20020719.tif" "data/chirps//20020720.tif"
 [51] "data/chirps//20020721.tif" "data/chirps//20020722.tif"
 [53] "data/chirps//20020723.tif" "data/chirps//20020724.tif"
 [55] "data/chirps//20020725.tif" "data/chirps//20020726.tif"
 [57] "data/chirps//20020727.tif" "data/chirps//20020728.tif"
 [59] "data/chirps//20020729.tif" "data/chirps//20020730.tif"
 [61] "data/chirps//20020731.tif" "data/chirps//20020801.tif"
 [63] "data/chirps//20020802.tif" "data/chirps//20020803.tif"
 [65] "data/chirps//20020804.tif" "data/chirps//20020805.tif"
 [67] "data/chirps//20020806.tif" "data/chirps//20020807.tif"
 [69] "data/chirps//20020808.tif" "data/chirps//20020809.tif"
 [71] "data/chirps//20020810.tif" "data/chirps//20020811.tif"
 [73] "data/chirps//20020812.tif" "data/chirps//20020813.tif"
 [75] "data/chirps//20020814.tif" "data/chirps//20020815.tif"
 [77] "data/chirps//20020816.tif" "data/chirps//20020817.tif"
 [79] "data/chirps//20020818.tif" "data/chirps//20020819.tif"
 [81] "data/chirps//20020820.tif" "data/chirps//20020821.tif"
 [83] "data/chirps//20020822.tif" "data/chirps//20020823.tif"
 [85] "data/chirps//20020824.tif" "data/chirps//20020825.tif"
 [87] "data/chirps//20020826.tif" "data/chirps//20020827.tif"
 [89] "data/chirps//20020828.tif" "data/chirps//20020829.tif"
 [91] "data/chirps//20020830.tif" "data/chirps//20020831.tif"
 [93] "data/chirps//20020901.tif" "data/chirps//20020902.tif"
 [95] "data/chirps//20020903.tif" "data/chirps//20020904.tif"
 [97] "data/chirps//20020905.tif" "data/chirps//20020906.tif"
 [99] "data/chirps//20020907.tif" "data/chirps//20020908.tif"
[101] "data/chirps//20020909.tif" "data/chirps//20020910.tif"
[103] "data/chirps//20020911.tif" "data/chirps//20020912.tif"
[105] "data/chirps//20020913.tif" "data/chirps//20020914.tif"
[107] "data/chirps//20020915.tif" "data/chirps//20020916.tif"
[109] "data/chirps//20020917.tif" "data/chirps//20020918.tif"
[111] "data/chirps//20020919.tif" "data/chirps//20020920.tif"
[113] "data/chirps//20020921.tif" "data/chirps//20020922.tif"
[115] "data/chirps//20020923.tif" "data/chirps//20020924.tif"
[117] "data/chirps//20020925.tif" "data/chirps//20020926.tif"
[119] "data/chirps//20020927.tif" "data/chirps//20020928.tif"
[121] "data/chirps//20020929.tif" "data/chirps//20020930.tif"

$`2003`
  [1] "data/chirps//20030601.tif" "data/chirps//20030602.tif"
  [3] "data/chirps//20030603.tif" "data/chirps//20030604.tif"
  [5] "data/chirps//20030605.tif" "data/chirps//20030606.tif"
  [7] "data/chirps//20030607.tif" "data/chirps//20030608.tif"
  [9] "data/chirps//20030609.tif" "data/chirps//20030610.tif"
 [11] "data/chirps//20030611.tif" "data/chirps//20030612.tif"
 [13] "data/chirps//20030613.tif" "data/chirps//20030614.tif"
 [15] "data/chirps//20030615.tif" "data/chirps//20030616.tif"
 [17] "data/chirps//20030617.tif" "data/chirps//20030618.tif"
 [19] "data/chirps//20030619.tif" "data/chirps//20030620.tif"
 [21] "data/chirps//20030621.tif" "data/chirps//20030622.tif"
 [23] "data/chirps//20030623.tif" "data/chirps//20030624.tif"
 [25] "data/chirps//20030625.tif" "data/chirps//20030626.tif"
 [27] "data/chirps//20030627.tif" "data/chirps//20030628.tif"
 [29] "data/chirps//20030629.tif" "data/chirps//20030630.tif"
 [31] "data/chirps//20030701.tif" "data/chirps//20030702.tif"
 [33] "data/chirps//20030703.tif" "data/chirps//20030704.tif"
 [35] "data/chirps//20030705.tif" "data/chirps//20030706.tif"
 [37] "data/chirps//20030707.tif" "data/chirps//20030708.tif"
 [39] "data/chirps//20030709.tif" "data/chirps//20030710.tif"
 [41] "data/chirps//20030711.tif" "data/chirps//20030712.tif"
 [43] "data/chirps//20030713.tif" "data/chirps//20030714.tif"
 [45] "data/chirps//20030715.tif" "data/chirps//20030716.tif"
 [47] "data/chirps//20030717.tif" "data/chirps//20030718.tif"
 [49] "data/chirps//20030719.tif" "data/chirps//20030720.tif"
 [51] "data/chirps//20030721.tif" "data/chirps//20030722.tif"
 [53] "data/chirps//20030723.tif" "data/chirps//20030724.tif"
 [55] "data/chirps//20030725.tif" "data/chirps//20030726.tif"
 [57] "data/chirps//20030727.tif" "data/chirps//20030728.tif"
 [59] "data/chirps//20030729.tif" "data/chirps//20030730.tif"
 [61] "data/chirps//20030731.tif" "data/chirps//20030801.tif"
 [63] "data/chirps//20030802.tif" "data/chirps//20030803.tif"
 [65] "data/chirps//20030804.tif" "data/chirps//20030805.tif"
 [67] "data/chirps//20030806.tif" "data/chirps//20030807.tif"
 [69] "data/chirps//20030808.tif" "data/chirps//20030809.tif"
 [71] "data/chirps//20030810.tif" "data/chirps//20030811.tif"
 [73] "data/chirps//20030812.tif" "data/chirps//20030813.tif"
 [75] "data/chirps//20030814.tif" "data/chirps//20030815.tif"
 [77] "data/chirps//20030816.tif" "data/chirps//20030817.tif"
 [79] "data/chirps//20030818.tif" "data/chirps//20030819.tif"
 [81] "data/chirps//20030820.tif" "data/chirps//20030821.tif"
 [83] "data/chirps//20030822.tif" "data/chirps//20030823.tif"
 [85] "data/chirps//20030824.tif" "data/chirps//20030825.tif"
 [87] "data/chirps//20030826.tif" "data/chirps//20030827.tif"
 [89] "data/chirps//20030828.tif" "data/chirps//20030829.tif"
 [91] "data/chirps//20030830.tif" "data/chirps//20030831.tif"
 [93] "data/chirps//20030901.tif" "data/chirps//20030902.tif"
 [95] "data/chirps//20030903.tif" "data/chirps//20030904.tif"
 [97] "data/chirps//20030905.tif" "data/chirps//20030906.tif"
 [99] "data/chirps//20030907.tif" "data/chirps//20030908.tif"
[101] "data/chirps//20030909.tif" "data/chirps//20030910.tif"
[103] "data/chirps//20030911.tif" "data/chirps//20030912.tif"
[105] "data/chirps//20030913.tif" "data/chirps//20030914.tif"
[107] "data/chirps//20030915.tif" "data/chirps//20030916.tif"
[109] "data/chirps//20030917.tif" "data/chirps//20030918.tif"
[111] "data/chirps//20030919.tif" "data/chirps//20030920.tif"
[113] "data/chirps//20030921.tif" "data/chirps//20030922.tif"
[115] "data/chirps//20030923.tif" "data/chirps//20030924.tif"
[117] "data/chirps//20030925.tif" "data/chirps//20030926.tif"
[119] "data/chirps//20030927.tif" "data/chirps//20030928.tif"
[121] "data/chirps//20030929.tif" "data/chirps//20030930.tif"

$`2004`
  [1] "data/chirps//20040601.tif" "data/chirps//20040602.tif"
  [3] "data/chirps//20040603.tif" "data/chirps//20040604.tif"
  [5] "data/chirps//20040605.tif" "data/chirps//20040606.tif"
  [7] "data/chirps//20040607.tif" "data/chirps//20040608.tif"
  [9] "data/chirps//20040609.tif" "data/chirps//20040610.tif"
 [11] "data/chirps//20040611.tif" "data/chirps//20040612.tif"
 [13] "data/chirps//20040613.tif" "data/chirps//20040614.tif"
 [15] "data/chirps//20040615.tif" "data/chirps//20040616.tif"
 [17] "data/chirps//20040617.tif" "data/chirps//20040618.tif"
 [19] "data/chirps//20040619.tif" "data/chirps//20040620.tif"
 [21] "data/chirps//20040621.tif" "data/chirps//20040622.tif"
 [23] "data/chirps//20040623.tif" "data/chirps//20040624.tif"
 [25] "data/chirps//20040625.tif" "data/chirps//20040626.tif"
 [27] "data/chirps//20040627.tif" "data/chirps//20040628.tif"
 [29] "data/chirps//20040629.tif" "data/chirps//20040630.tif"
 [31] "data/chirps//20040701.tif" "data/chirps//20040702.tif"
 [33] "data/chirps//20040703.tif" "data/chirps//20040704.tif"
 [35] "data/chirps//20040705.tif" "data/chirps//20040706.tif"
 [37] "data/chirps//20040707.tif" "data/chirps//20040708.tif"
 [39] "data/chirps//20040709.tif" "data/chirps//20040710.tif"
 [41] "data/chirps//20040711.tif" "data/chirps//20040712.tif"
 [43] "data/chirps//20040713.tif" "data/chirps//20040714.tif"
 [45] "data/chirps//20040715.tif" "data/chirps//20040716.tif"
 [47] "data/chirps//20040717.tif" "data/chirps//20040718.tif"
 [49] "data/chirps//20040719.tif" "data/chirps//20040720.tif"
 [51] "data/chirps//20040721.tif" "data/chirps//20040722.tif"
 [53] "data/chirps//20040723.tif" "data/chirps//20040724.tif"
 [55] "data/chirps//20040725.tif" "data/chirps//20040726.tif"
 [57] "data/chirps//20040727.tif" "data/chirps//20040728.tif"
 [59] "data/chirps//20040729.tif" "data/chirps//20040730.tif"
 [61] "data/chirps//20040731.tif" "data/chirps//20040801.tif"
 [63] "data/chirps//20040802.tif" "data/chirps//20040803.tif"
 [65] "data/chirps//20040804.tif" "data/chirps//20040805.tif"
 [67] "data/chirps//20040806.tif" "data/chirps//20040807.tif"
 [69] "data/chirps//20040808.tif" "data/chirps//20040809.tif"
 [71] "data/chirps//20040810.tif" "data/chirps//20040811.tif"
 [73] "data/chirps//20040812.tif" "data/chirps//20040813.tif"
 [75] "data/chirps//20040814.tif" "data/chirps//20040815.tif"
 [77] "data/chirps//20040816.tif" "data/chirps//20040817.tif"
 [79] "data/chirps//20040818.tif" "data/chirps//20040819.tif"
 [81] "data/chirps//20040820.tif" "data/chirps//20040821.tif"
 [83] "data/chirps//20040822.tif" "data/chirps//20040823.tif"
 [85] "data/chirps//20040824.tif" "data/chirps//20040825.tif"
 [87] "data/chirps//20040826.tif" "data/chirps//20040827.tif"
 [89] "data/chirps//20040828.tif" "data/chirps//20040829.tif"
 [91] "data/chirps//20040830.tif" "data/chirps//20040831.tif"
 [93] "data/chirps//20040901.tif" "data/chirps//20040902.tif"
 [95] "data/chirps//20040903.tif" "data/chirps//20040904.tif"
 [97] "data/chirps//20040905.tif" "data/chirps//20040906.tif"
 [99] "data/chirps//20040907.tif" "data/chirps//20040908.tif"
[101] "data/chirps//20040909.tif" "data/chirps//20040910.tif"
[103] "data/chirps//20040911.tif" "data/chirps//20040912.tif"
[105] "data/chirps//20040913.tif" "data/chirps//20040914.tif"
[107] "data/chirps//20040915.tif" "data/chirps//20040916.tif"
[109] "data/chirps//20040917.tif" "data/chirps//20040918.tif"
[111] "data/chirps//20040919.tif" "data/chirps//20040920.tif"
[113] "data/chirps//20040921.tif" "data/chirps//20040922.tif"
[115] "data/chirps//20040923.tif" "data/chirps//20040924.tif"
[117] "data/chirps//20040925.tif" "data/chirps//20040926.tif"
[119] "data/chirps//20040927.tif" "data/chirps//20040928.tif"
[121] "data/chirps//20040929.tif" "data/chirps//20040930.tif"

$`2005`
  [1] "data/chirps//20050601.tif" "data/chirps//20050602.tif"
  [3] "data/chirps//20050603.tif" "data/chirps//20050604.tif"
  [5] "data/chirps//20050605.tif" "data/chirps//20050606.tif"
  [7] "data/chirps//20050607.tif" "data/chirps//20050608.tif"
  [9] "data/chirps//20050609.tif" "data/chirps//20050610.tif"
 [11] "data/chirps//20050611.tif" "data/chirps//20050612.tif"
 [13] "data/chirps//20050613.tif" "data/chirps//20050614.tif"
 [15] "data/chirps//20050615.tif" "data/chirps//20050616.tif"
 [17] "data/chirps//20050617.tif" "data/chirps//20050618.tif"
 [19] "data/chirps//20050619.tif" "data/chirps//20050620.tif"
 [21] "data/chirps//20050621.tif" "data/chirps//20050622.tif"
 [23] "data/chirps//20050623.tif" "data/chirps//20050624.tif"
 [25] "data/chirps//20050625.tif" "data/chirps//20050626.tif"
 [27] "data/chirps//20050627.tif" "data/chirps//20050628.tif"
 [29] "data/chirps//20050629.tif" "data/chirps//20050630.tif"
 [31] "data/chirps//20050701.tif" "data/chirps//20050702.tif"
 [33] "data/chirps//20050703.tif" "data/chirps//20050704.tif"
 [35] "data/chirps//20050705.tif" "data/chirps//20050706.tif"
 [37] "data/chirps//20050707.tif" "data/chirps//20050708.tif"
 [39] "data/chirps//20050709.tif" "data/chirps//20050710.tif"
 [41] "data/chirps//20050711.tif" "data/chirps//20050712.tif"
 [43] "data/chirps//20050713.tif" "data/chirps//20050714.tif"
 [45] "data/chirps//20050715.tif" "data/chirps//20050716.tif"
 [47] "data/chirps//20050717.tif" "data/chirps//20050718.tif"
 [49] "data/chirps//20050719.tif" "data/chirps//20050720.tif"
 [51] "data/chirps//20050721.tif" "data/chirps//20050722.tif"
 [53] "data/chirps//20050723.tif" "data/chirps//20050724.tif"
 [55] "data/chirps//20050725.tif" "data/chirps//20050726.tif"
 [57] "data/chirps//20050727.tif" "data/chirps//20050728.tif"
 [59] "data/chirps//20050729.tif" "data/chirps//20050730.tif"
 [61] "data/chirps//20050731.tif" "data/chirps//20050801.tif"
 [63] "data/chirps//20050802.tif" "data/chirps//20050803.tif"
 [65] "data/chirps//20050804.tif" "data/chirps//20050805.tif"
 [67] "data/chirps//20050806.tif" "data/chirps//20050807.tif"
 [69] "data/chirps//20050808.tif" "data/chirps//20050809.tif"
 [71] "data/chirps//20050810.tif" "data/chirps//20050811.tif"
 [73] "data/chirps//20050812.tif" "data/chirps//20050813.tif"
 [75] "data/chirps//20050814.tif" "data/chirps//20050815.tif"
 [77] "data/chirps//20050816.tif" "data/chirps//20050817.tif"
 [79] "data/chirps//20050818.tif" "data/chirps//20050819.tif"
 [81] "data/chirps//20050820.tif" "data/chirps//20050821.tif"
 [83] "data/chirps//20050822.tif" "data/chirps//20050823.tif"
 [85] "data/chirps//20050824.tif" "data/chirps//20050825.tif"
 [87] "data/chirps//20050826.tif" "data/chirps//20050827.tif"
 [89] "data/chirps//20050828.tif" "data/chirps//20050829.tif"
 [91] "data/chirps//20050830.tif" "data/chirps//20050831.tif"
 [93] "data/chirps//20050901.tif" "data/chirps//20050902.tif"
 [95] "data/chirps//20050903.tif" "data/chirps//20050904.tif"
 [97] "data/chirps//20050905.tif" "data/chirps//20050906.tif"
 [99] "data/chirps//20050907.tif" "data/chirps//20050908.tif"
[101] "data/chirps//20050909.tif" "data/chirps//20050910.tif"
[103] "data/chirps//20050911.tif" "data/chirps//20050912.tif"
[105] "data/chirps//20050913.tif" "data/chirps//20050914.tif"
[107] "data/chirps//20050915.tif" "data/chirps//20050916.tif"
[109] "data/chirps//20050917.tif" "data/chirps//20050918.tif"
[111] "data/chirps//20050919.tif" "data/chirps//20050920.tif"
[113] "data/chirps//20050921.tif" "data/chirps//20050922.tif"
[115] "data/chirps//20050923.tif" "data/chirps//20050924.tif"
[117] "data/chirps//20050925.tif" "data/chirps//20050926.tif"
[119] "data/chirps//20050927.tif" "data/chirps//20050928.tif"
[121] "data/chirps//20050929.tif" "data/chirps//20050930.tif"

$`2006`
  [1] "data/chirps//20060601.tif" "data/chirps//20060602.tif"
  [3] "data/chirps//20060603.tif" "data/chirps//20060604.tif"
  [5] "data/chirps//20060605.tif" "data/chirps//20060606.tif"
  [7] "data/chirps//20060607.tif" "data/chirps//20060608.tif"
  [9] "data/chirps//20060609.tif" "data/chirps//20060610.tif"
 [11] "data/chirps//20060611.tif" "data/chirps//20060612.tif"
 [13] "data/chirps//20060613.tif" "data/chirps//20060614.tif"
 [15] "data/chirps//20060615.tif" "data/chirps//20060616.tif"
 [17] "data/chirps//20060617.tif" "data/chirps//20060618.tif"
 [19] "data/chirps//20060619.tif" "data/chirps//20060620.tif"
 [21] "data/chirps//20060621.tif" "data/chirps//20060622.tif"
 [23] "data/chirps//20060623.tif" "data/chirps//20060624.tif"
 [25] "data/chirps//20060625.tif" "data/chirps//20060626.tif"
 [27] "data/chirps//20060627.tif" "data/chirps//20060628.tif"
 [29] "data/chirps//20060629.tif" "data/chirps//20060630.tif"
 [31] "data/chirps//20060701.tif" "data/chirps//20060702.tif"
 [33] "data/chirps//20060703.tif" "data/chirps//20060704.tif"
 [35] "data/chirps//20060705.tif" "data/chirps//20060706.tif"
 [37] "data/chirps//20060707.tif" "data/chirps//20060708.tif"
 [39] "data/chirps//20060709.tif" "data/chirps//20060710.tif"
 [41] "data/chirps//20060711.tif" "data/chirps//20060712.tif"
 [43] "data/chirps//20060713.tif" "data/chirps//20060714.tif"
 [45] "data/chirps//20060715.tif" "data/chirps//20060716.tif"
 [47] "data/chirps//20060717.tif" "data/chirps//20060718.tif"
 [49] "data/chirps//20060719.tif" "data/chirps//20060720.tif"
 [51] "data/chirps//20060721.tif" "data/chirps//20060722.tif"
 [53] "data/chirps//20060723.tif" "data/chirps//20060724.tif"
 [55] "data/chirps//20060725.tif" "data/chirps//20060726.tif"
 [57] "data/chirps//20060727.tif" "data/chirps//20060728.tif"
 [59] "data/chirps//20060729.tif" "data/chirps//20060730.tif"
 [61] "data/chirps//20060731.tif" "data/chirps//20060801.tif"
 [63] "data/chirps//20060802.tif" "data/chirps//20060803.tif"
 [65] "data/chirps//20060804.tif" "data/chirps//20060805.tif"
 [67] "data/chirps//20060806.tif" "data/chirps//20060807.tif"
 [69] "data/chirps//20060808.tif" "data/chirps//20060809.tif"
 [71] "data/chirps//20060810.tif" "data/chirps//20060811.tif"
 [73] "data/chirps//20060812.tif" "data/chirps//20060813.tif"
 [75] "data/chirps//20060814.tif" "data/chirps//20060815.tif"
 [77] "data/chirps//20060816.tif" "data/chirps//20060817.tif"
 [79] "data/chirps//20060818.tif" "data/chirps//20060819.tif"
 [81] "data/chirps//20060820.tif" "data/chirps//20060821.tif"
 [83] "data/chirps//20060822.tif" "data/chirps//20060823.tif"
 [85] "data/chirps//20060824.tif" "data/chirps//20060825.tif"
 [87] "data/chirps//20060826.tif" "data/chirps//20060827.tif"
 [89] "data/chirps//20060828.tif" "data/chirps//20060829.tif"
 [91] "data/chirps//20060830.tif" "data/chirps//20060831.tif"
 [93] "data/chirps//20060901.tif" "data/chirps//20060902.tif"
 [95] "data/chirps//20060903.tif" "data/chirps//20060904.tif"
 [97] "data/chirps//20060905.tif" "data/chirps//20060906.tif"
 [99] "data/chirps//20060907.tif" "data/chirps//20060908.tif"
[101] "data/chirps//20060909.tif" "data/chirps//20060910.tif"
[103] "data/chirps//20060911.tif" "data/chirps//20060912.tif"
[105] "data/chirps//20060913.tif" "data/chirps//20060914.tif"
[107] "data/chirps//20060915.tif" "data/chirps//20060916.tif"
[109] "data/chirps//20060917.tif" "data/chirps//20060918.tif"
[111] "data/chirps//20060919.tif" "data/chirps//20060920.tif"
[113] "data/chirps//20060921.tif" "data/chirps//20060922.tif"
[115] "data/chirps//20060923.tif" "data/chirps//20060924.tif"
[117] "data/chirps//20060925.tif" "data/chirps//20060926.tif"
[119] "data/chirps//20060927.tif" "data/chirps//20060928.tif"
[121] "data/chirps//20060929.tif" "data/chirps//20060930.tif"

$`2007`
  [1] "data/chirps//20070601.tif" "data/chirps//20070602.tif"
  [3] "data/chirps//20070603.tif" "data/chirps//20070604.tif"
  [5] "data/chirps//20070605.tif" "data/chirps//20070606.tif"
  [7] "data/chirps//20070607.tif" "data/chirps//20070608.tif"
  [9] "data/chirps//20070609.tif" "data/chirps//20070610.tif"
 [11] "data/chirps//20070611.tif" "data/chirps//20070612.tif"
 [13] "data/chirps//20070613.tif" "data/chirps//20070614.tif"
 [15] "data/chirps//20070615.tif" "data/chirps//20070616.tif"
 [17] "data/chirps//20070617.tif" "data/chirps//20070618.tif"
 [19] "data/chirps//20070619.tif" "data/chirps//20070620.tif"
 [21] "data/chirps//20070621.tif" "data/chirps//20070622.tif"
 [23] "data/chirps//20070623.tif" "data/chirps//20070624.tif"
 [25] "data/chirps//20070625.tif" "data/chirps//20070626.tif"
 [27] "data/chirps//20070627.tif" "data/chirps//20070628.tif"
 [29] "data/chirps//20070629.tif" "data/chirps//20070630.tif"
 [31] "data/chirps//20070701.tif" "data/chirps//20070702.tif"
 [33] "data/chirps//20070703.tif" "data/chirps//20070704.tif"
 [35] "data/chirps//20070705.tif" "data/chirps//20070706.tif"
 [37] "data/chirps//20070707.tif" "data/chirps//20070708.tif"
 [39] "data/chirps//20070709.tif" "data/chirps//20070710.tif"
 [41] "data/chirps//20070711.tif" "data/chirps//20070712.tif"
 [43] "data/chirps//20070713.tif" "data/chirps//20070714.tif"
 [45] "data/chirps//20070715.tif" "data/chirps//20070716.tif"
 [47] "data/chirps//20070717.tif" "data/chirps//20070718.tif"
 [49] "data/chirps//20070719.tif" "data/chirps//20070720.tif"
 [51] "data/chirps//20070721.tif" "data/chirps//20070722.tif"
 [53] "data/chirps//20070723.tif" "data/chirps//20070724.tif"
 [55] "data/chirps//20070725.tif" "data/chirps//20070726.tif"
 [57] "data/chirps//20070727.tif" "data/chirps//20070728.tif"
 [59] "data/chirps//20070729.tif" "data/chirps//20070730.tif"
 [61] "data/chirps//20070731.tif" "data/chirps//20070801.tif"
 [63] "data/chirps//20070802.tif" "data/chirps//20070803.tif"
 [65] "data/chirps//20070804.tif" "data/chirps//20070805.tif"
 [67] "data/chirps//20070806.tif" "data/chirps//20070807.tif"
 [69] "data/chirps//20070808.tif" "data/chirps//20070809.tif"
 [71] "data/chirps//20070810.tif" "data/chirps//20070811.tif"
 [73] "data/chirps//20070812.tif" "data/chirps//20070813.tif"
 [75] "data/chirps//20070814.tif" "data/chirps//20070815.tif"
 [77] "data/chirps//20070816.tif" "data/chirps//20070817.tif"
 [79] "data/chirps//20070818.tif" "data/chirps//20070819.tif"
 [81] "data/chirps//20070820.tif" "data/chirps//20070821.tif"
 [83] "data/chirps//20070822.tif" "data/chirps//20070823.tif"
 [85] "data/chirps//20070824.tif" "data/chirps//20070825.tif"
 [87] "data/chirps//20070826.tif" "data/chirps//20070827.tif"
 [89] "data/chirps//20070828.tif" "data/chirps//20070829.tif"
 [91] "data/chirps//20070830.tif" "data/chirps//20070831.tif"
 [93] "data/chirps//20070901.tif" "data/chirps//20070902.tif"
 [95] "data/chirps//20070903.tif" "data/chirps//20070904.tif"
 [97] "data/chirps//20070905.tif" "data/chirps//20070906.tif"
 [99] "data/chirps//20070907.tif" "data/chirps//20070908.tif"
[101] "data/chirps//20070909.tif" "data/chirps//20070910.tif"
[103] "data/chirps//20070911.tif" "data/chirps//20070912.tif"
[105] "data/chirps//20070913.tif" "data/chirps//20070914.tif"
[107] "data/chirps//20070915.tif" "data/chirps//20070916.tif"
[109] "data/chirps//20070917.tif" "data/chirps//20070918.tif"
[111] "data/chirps//20070919.tif" "data/chirps//20070920.tif"
[113] "data/chirps//20070921.tif" "data/chirps//20070922.tif"
[115] "data/chirps//20070923.tif" "data/chirps//20070924.tif"
[117] "data/chirps//20070925.tif" "data/chirps//20070926.tif"
[119] "data/chirps//20070927.tif" "data/chirps//20070928.tif"
[121] "data/chirps//20070929.tif" "data/chirps//20070930.tif"

$`2008`
  [1] "data/chirps//20080601.tif" "data/chirps//20080602.tif"
  [3] "data/chirps//20080603.tif" "data/chirps//20080604.tif"
  [5] "data/chirps//20080605.tif" "data/chirps//20080606.tif"
  [7] "data/chirps//20080607.tif" "data/chirps//20080608.tif"
  [9] "data/chirps//20080609.tif" "data/chirps//20080610.tif"
 [11] "data/chirps//20080611.tif" "data/chirps//20080612.tif"
 [13] "data/chirps//20080613.tif" "data/chirps//20080614.tif"
 [15] "data/chirps//20080615.tif" "data/chirps//20080616.tif"
 [17] "data/chirps//20080617.tif" "data/chirps//20080618.tif"
 [19] "data/chirps//20080619.tif" "data/chirps//20080620.tif"
 [21] "data/chirps//20080621.tif" "data/chirps//20080622.tif"
 [23] "data/chirps//20080623.tif" "data/chirps//20080624.tif"
 [25] "data/chirps//20080625.tif" "data/chirps//20080626.tif"
 [27] "data/chirps//20080627.tif" "data/chirps//20080628.tif"
 [29] "data/chirps//20080629.tif" "data/chirps//20080630.tif"
 [31] "data/chirps//20080701.tif" "data/chirps//20080702.tif"
 [33] "data/chirps//20080703.tif" "data/chirps//20080704.tif"
 [35] "data/chirps//20080705.tif" "data/chirps//20080706.tif"
 [37] "data/chirps//20080707.tif" "data/chirps//20080708.tif"
 [39] "data/chirps//20080709.tif" "data/chirps//20080710.tif"
 [41] "data/chirps//20080711.tif" "data/chirps//20080712.tif"
 [43] "data/chirps//20080713.tif" "data/chirps//20080714.tif"
 [45] "data/chirps//20080715.tif" "data/chirps//20080716.tif"
 [47] "data/chirps//20080717.tif" "data/chirps//20080718.tif"
 [49] "data/chirps//20080719.tif" "data/chirps//20080720.tif"
 [51] "data/chirps//20080721.tif" "data/chirps//20080722.tif"
 [53] "data/chirps//20080723.tif" "data/chirps//20080724.tif"
 [55] "data/chirps//20080725.tif" "data/chirps//20080726.tif"
 [57] "data/chirps//20080727.tif" "data/chirps//20080728.tif"
 [59] "data/chirps//20080729.tif" "data/chirps//20080730.tif"
 [61] "data/chirps//20080731.tif" "data/chirps//20080801.tif"
 [63] "data/chirps//20080802.tif" "data/chirps//20080803.tif"
 [65] "data/chirps//20080804.tif" "data/chirps//20080805.tif"
 [67] "data/chirps//20080806.tif" "data/chirps//20080807.tif"
 [69] "data/chirps//20080808.tif" "data/chirps//20080809.tif"
 [71] "data/chirps//20080810.tif" "data/chirps//20080811.tif"
 [73] "data/chirps//20080812.tif" "data/chirps//20080813.tif"
 [75] "data/chirps//20080814.tif" "data/chirps//20080815.tif"
 [77] "data/chirps//20080816.tif" "data/chirps//20080817.tif"
 [79] "data/chirps//20080818.tif" "data/chirps//20080819.tif"
 [81] "data/chirps//20080820.tif" "data/chirps//20080821.tif"
 [83] "data/chirps//20080822.tif" "data/chirps//20080823.tif"
 [85] "data/chirps//20080824.tif" "data/chirps//20080825.tif"
 [87] "data/chirps//20080826.tif" "data/chirps//20080827.tif"
 [89] "data/chirps//20080828.tif" "data/chirps//20080829.tif"
 [91] "data/chirps//20080830.tif" "data/chirps//20080831.tif"
 [93] "data/chirps//20080901.tif" "data/chirps//20080902.tif"
 [95] "data/chirps//20080903.tif" "data/chirps//20080904.tif"
 [97] "data/chirps//20080905.tif" "data/chirps//20080906.tif"
 [99] "data/chirps//20080907.tif" "data/chirps//20080908.tif"
[101] "data/chirps//20080909.tif" "data/chirps//20080910.tif"
[103] "data/chirps//20080911.tif" "data/chirps//20080912.tif"
[105] "data/chirps//20080913.tif" "data/chirps//20080914.tif"
[107] "data/chirps//20080915.tif" "data/chirps//20080916.tif"
[109] "data/chirps//20080917.tif" "data/chirps//20080918.tif"
[111] "data/chirps//20080919.tif" "data/chirps//20080920.tif"
[113] "data/chirps//20080921.tif" "data/chirps//20080922.tif"
[115] "data/chirps//20080923.tif" "data/chirps//20080924.tif"
[117] "data/chirps//20080925.tif" "data/chirps//20080926.tif"
[119] "data/chirps//20080927.tif" "data/chirps//20080928.tif"
[121] "data/chirps//20080929.tif" "data/chirps//20080930.tif"

$`2009`
  [1] "data/chirps//20090601.tif" "data/chirps//20090602.tif"
  [3] "data/chirps//20090603.tif" "data/chirps//20090604.tif"
  [5] "data/chirps//20090605.tif" "data/chirps//20090606.tif"
  [7] "data/chirps//20090607.tif" "data/chirps//20090608.tif"
  [9] "data/chirps//20090609.tif" "data/chirps//20090610.tif"
 [11] "data/chirps//20090611.tif" "data/chirps//20090612.tif"
 [13] "data/chirps//20090613.tif" "data/chirps//20090614.tif"
 [15] "data/chirps//20090615.tif" "data/chirps//20090616.tif"
 [17] "data/chirps//20090617.tif" "data/chirps//20090618.tif"
 [19] "data/chirps//20090619.tif" "data/chirps//20090620.tif"
 [21] "data/chirps//20090621.tif" "data/chirps//20090622.tif"
 [23] "data/chirps//20090623.tif" "data/chirps//20090624.tif"
 [25] "data/chirps//20090625.tif" "data/chirps//20090626.tif"
 [27] "data/chirps//20090627.tif" "data/chirps//20090628.tif"
 [29] "data/chirps//20090629.tif" "data/chirps//20090630.tif"
 [31] "data/chirps//20090701.tif" "data/chirps//20090702.tif"
 [33] "data/chirps//20090703.tif" "data/chirps//20090704.tif"
 [35] "data/chirps//20090705.tif" "data/chirps//20090706.tif"
 [37] "data/chirps//20090707.tif" "data/chirps//20090708.tif"
 [39] "data/chirps//20090709.tif" "data/chirps//20090710.tif"
 [41] "data/chirps//20090711.tif" "data/chirps//20090712.tif"
 [43] "data/chirps//20090713.tif" "data/chirps//20090714.tif"
 [45] "data/chirps//20090715.tif" "data/chirps//20090716.tif"
 [47] "data/chirps//20090717.tif" "data/chirps//20090718.tif"
 [49] "data/chirps//20090719.tif" "data/chirps//20090720.tif"
 [51] "data/chirps//20090721.tif" "data/chirps//20090722.tif"
 [53] "data/chirps//20090723.tif" "data/chirps//20090724.tif"
 [55] "data/chirps//20090725.tif" "data/chirps//20090726.tif"
 [57] "data/chirps//20090727.tif" "data/chirps//20090728.tif"
 [59] "data/chirps//20090729.tif" "data/chirps//20090730.tif"
 [61] "data/chirps//20090731.tif" "data/chirps//20090801.tif"
 [63] "data/chirps//20090802.tif" "data/chirps//20090803.tif"
 [65] "data/chirps//20090804.tif" "data/chirps//20090805.tif"
 [67] "data/chirps//20090806.tif" "data/chirps//20090807.tif"
 [69] "data/chirps//20090808.tif" "data/chirps//20090809.tif"
 [71] "data/chirps//20090810.tif" "data/chirps//20090811.tif"
 [73] "data/chirps//20090812.tif" "data/chirps//20090813.tif"
 [75] "data/chirps//20090814.tif" "data/chirps//20090815.tif"
 [77] "data/chirps//20090816.tif" "data/chirps//20090817.tif"
 [79] "data/chirps//20090818.tif" "data/chirps//20090819.tif"
 [81] "data/chirps//20090820.tif" "data/chirps//20090821.tif"
 [83] "data/chirps//20090822.tif" "data/chirps//20090823.tif"
 [85] "data/chirps//20090824.tif" "data/chirps//20090825.tif"
 [87] "data/chirps//20090826.tif" "data/chirps//20090827.tif"
 [89] "data/chirps//20090828.tif" "data/chirps//20090829.tif"
 [91] "data/chirps//20090830.tif" "data/chirps//20090831.tif"
 [93] "data/chirps//20090901.tif" "data/chirps//20090902.tif"
 [95] "data/chirps//20090903.tif" "data/chirps//20090904.tif"
 [97] "data/chirps//20090905.tif" "data/chirps//20090906.tif"
 [99] "data/chirps//20090907.tif" "data/chirps//20090908.tif"
[101] "data/chirps//20090909.tif" "data/chirps//20090910.tif"
[103] "data/chirps//20090911.tif" "data/chirps//20090912.tif"
[105] "data/chirps//20090913.tif" "data/chirps//20090914.tif"
[107] "data/chirps//20090915.tif" "data/chirps//20090916.tif"
[109] "data/chirps//20090917.tif" "data/chirps//20090918.tif"
[111] "data/chirps//20090919.tif" "data/chirps//20090920.tif"
[113] "data/chirps//20090921.tif" "data/chirps//20090922.tif"
[115] "data/chirps//20090923.tif" "data/chirps//20090924.tif"
[117] "data/chirps//20090925.tif" "data/chirps//20090926.tif"
[119] "data/chirps//20090927.tif" "data/chirps//20090928.tif"
[121] "data/chirps//20090929.tif" "data/chirps//20090930.tif"

$`2010`
  [1] "data/chirps//20100601.tif" "data/chirps//20100602.tif"
  [3] "data/chirps//20100603.tif" "data/chirps//20100604.tif"
  [5] "data/chirps//20100605.tif" "data/chirps//20100606.tif"
  [7] "data/chirps//20100607.tif" "data/chirps//20100608.tif"
  [9] "data/chirps//20100609.tif" "data/chirps//20100610.tif"
 [11] "data/chirps//20100611.tif" "data/chirps//20100612.tif"
 [13] "data/chirps//20100613.tif" "data/chirps//20100614.tif"
 [15] "data/chirps//20100615.tif" "data/chirps//20100616.tif"
 [17] "data/chirps//20100617.tif" "data/chirps//20100618.tif"
 [19] "data/chirps//20100619.tif" "data/chirps//20100620.tif"
 [21] "data/chirps//20100621.tif" "data/chirps//20100622.tif"
 [23] "data/chirps//20100623.tif" "data/chirps//20100624.tif"
 [25] "data/chirps//20100625.tif" "data/chirps//20100626.tif"
 [27] "data/chirps//20100627.tif" "data/chirps//20100628.tif"
 [29] "data/chirps//20100629.tif" "data/chirps//20100630.tif"
 [31] "data/chirps//20100701.tif" "data/chirps//20100702.tif"
 [33] "data/chirps//20100703.tif" "data/chirps//20100704.tif"
 [35] "data/chirps//20100705.tif" "data/chirps//20100706.tif"
 [37] "data/chirps//20100707.tif" "data/chirps//20100708.tif"
 [39] "data/chirps//20100709.tif" "data/chirps//20100710.tif"
 [41] "data/chirps//20100711.tif" "data/chirps//20100712.tif"
 [43] "data/chirps//20100713.tif" "data/chirps//20100714.tif"
 [45] "data/chirps//20100715.tif" "data/chirps//20100716.tif"
 [47] "data/chirps//20100717.tif" "data/chirps//20100718.tif"
 [49] "data/chirps//20100719.tif" "data/chirps//20100720.tif"
 [51] "data/chirps//20100721.tif" "data/chirps//20100722.tif"
 [53] "data/chirps//20100723.tif" "data/chirps//20100724.tif"
 [55] "data/chirps//20100725.tif" "data/chirps//20100726.tif"
 [57] "data/chirps//20100727.tif" "data/chirps//20100728.tif"
 [59] "data/chirps//20100729.tif" "data/chirps//20100730.tif"
 [61] "data/chirps//20100731.tif" "data/chirps//20100801.tif"
 [63] "data/chirps//20100802.tif" "data/chirps//20100803.tif"
 [65] "data/chirps//20100804.tif" "data/chirps//20100805.tif"
 [67] "data/chirps//20100806.tif" "data/chirps//20100807.tif"
 [69] "data/chirps//20100808.tif" "data/chirps//20100809.tif"
 [71] "data/chirps//20100810.tif" "data/chirps//20100811.tif"
 [73] "data/chirps//20100812.tif" "data/chirps//20100813.tif"
 [75] "data/chirps//20100814.tif" "data/chirps//20100815.tif"
 [77] "data/chirps//20100816.tif" "data/chirps//20100817.tif"
 [79] "data/chirps//20100818.tif" "data/chirps//20100819.tif"
 [81] "data/chirps//20100820.tif" "data/chirps//20100821.tif"
 [83] "data/chirps//20100822.tif" "data/chirps//20100823.tif"
 [85] "data/chirps//20100824.tif" "data/chirps//20100825.tif"
 [87] "data/chirps//20100826.tif" "data/chirps//20100827.tif"
 [89] "data/chirps//20100828.tif" "data/chirps//20100829.tif"
 [91] "data/chirps//20100830.tif" "data/chirps//20100831.tif"
 [93] "data/chirps//20100901.tif" "data/chirps//20100902.tif"
 [95] "data/chirps//20100903.tif" "data/chirps//20100904.tif"
 [97] "data/chirps//20100905.tif" "data/chirps//20100906.tif"
 [99] "data/chirps//20100907.tif" "data/chirps//20100908.tif"
[101] "data/chirps//20100909.tif" "data/chirps//20100910.tif"
[103] "data/chirps//20100911.tif" "data/chirps//20100912.tif"
[105] "data/chirps//20100913.tif" "data/chirps//20100914.tif"
[107] "data/chirps//20100915.tif" "data/chirps//20100916.tif"
[109] "data/chirps//20100917.tif" "data/chirps//20100918.tif"
[111] "data/chirps//20100919.tif" "data/chirps//20100920.tif"
[113] "data/chirps//20100921.tif" "data/chirps//20100922.tif"
[115] "data/chirps//20100923.tif" "data/chirps//20100924.tif"
[117] "data/chirps//20100925.tif" "data/chirps//20100926.tif"
[119] "data/chirps//20100927.tif" "data/chirps//20100928.tif"
[121] "data/chirps//20100929.tif" "data/chirps//20100930.tif"

$`2011`
  [1] "data/chirps//20110601.tif" "data/chirps//20110602.tif"
  [3] "data/chirps//20110603.tif" "data/chirps//20110604.tif"
  [5] "data/chirps//20110605.tif" "data/chirps//20110606.tif"
  [7] "data/chirps//20110607.tif" "data/chirps//20110608.tif"
  [9] "data/chirps//20110609.tif" "data/chirps//20110610.tif"
 [11] "data/chirps//20110611.tif" "data/chirps//20110612.tif"
 [13] "data/chirps//20110613.tif" "data/chirps//20110614.tif"
 [15] "data/chirps//20110615.tif" "data/chirps//20110616.tif"
 [17] "data/chirps//20110617.tif" "data/chirps//20110618.tif"
 [19] "data/chirps//20110619.tif" "data/chirps//20110620.tif"
 [21] "data/chirps//20110621.tif" "data/chirps//20110622.tif"
 [23] "data/chirps//20110623.tif" "data/chirps//20110624.tif"
 [25] "data/chirps//20110625.tif" "data/chirps//20110626.tif"
 [27] "data/chirps//20110627.tif" "data/chirps//20110628.tif"
 [29] "data/chirps//20110629.tif" "data/chirps//20110630.tif"
 [31] "data/chirps//20110701.tif" "data/chirps//20110702.tif"
 [33] "data/chirps//20110703.tif" "data/chirps//20110704.tif"
 [35] "data/chirps//20110705.tif" "data/chirps//20110706.tif"
 [37] "data/chirps//20110707.tif" "data/chirps//20110708.tif"
 [39] "data/chirps//20110709.tif" "data/chirps//20110710.tif"
 [41] "data/chirps//20110711.tif" "data/chirps//20110712.tif"
 [43] "data/chirps//20110713.tif" "data/chirps//20110714.tif"
 [45] "data/chirps//20110715.tif" "data/chirps//20110716.tif"
 [47] "data/chirps//20110717.tif" "data/chirps//20110718.tif"
 [49] "data/chirps//20110719.tif" "data/chirps//20110720.tif"
 [51] "data/chirps//20110721.tif" "data/chirps//20110722.tif"
 [53] "data/chirps//20110723.tif" "data/chirps//20110724.tif"
 [55] "data/chirps//20110725.tif" "data/chirps//20110726.tif"
 [57] "data/chirps//20110727.tif" "data/chirps//20110728.tif"
 [59] "data/chirps//20110729.tif" "data/chirps//20110730.tif"
 [61] "data/chirps//20110731.tif" "data/chirps//20110801.tif"
 [63] "data/chirps//20110802.tif" "data/chirps//20110803.tif"
 [65] "data/chirps//20110804.tif" "data/chirps//20110805.tif"
 [67] "data/chirps//20110806.tif" "data/chirps//20110807.tif"
 [69] "data/chirps//20110808.tif" "data/chirps//20110809.tif"
 [71] "data/chirps//20110810.tif" "data/chirps//20110811.tif"
 [73] "data/chirps//20110812.tif" "data/chirps//20110813.tif"
 [75] "data/chirps//20110814.tif" "data/chirps//20110815.tif"
 [77] "data/chirps//20110816.tif" "data/chirps//20110817.tif"
 [79] "data/chirps//20110818.tif" "data/chirps//20110819.tif"
 [81] "data/chirps//20110820.tif" "data/chirps//20110821.tif"
 [83] "data/chirps//20110822.tif" "data/chirps//20110823.tif"
 [85] "data/chirps//20110824.tif" "data/chirps//20110825.tif"
 [87] "data/chirps//20110826.tif" "data/chirps//20110827.tif"
 [89] "data/chirps//20110828.tif" "data/chirps//20110829.tif"
 [91] "data/chirps//20110830.tif" "data/chirps//20110831.tif"
 [93] "data/chirps//20110901.tif" "data/chirps//20110902.tif"
 [95] "data/chirps//20110903.tif" "data/chirps//20110904.tif"
 [97] "data/chirps//20110905.tif" "data/chirps//20110906.tif"
 [99] "data/chirps//20110907.tif" "data/chirps//20110908.tif"
[101] "data/chirps//20110909.tif" "data/chirps//20110910.tif"
[103] "data/chirps//20110911.tif" "data/chirps//20110912.tif"
[105] "data/chirps//20110913.tif" "data/chirps//20110914.tif"
[107] "data/chirps//20110915.tif" "data/chirps//20110916.tif"
[109] "data/chirps//20110917.tif" "data/chirps//20110918.tif"
[111] "data/chirps//20110919.tif" "data/chirps//20110920.tif"
[113] "data/chirps//20110921.tif" "data/chirps//20110922.tif"
[115] "data/chirps//20110923.tif" "data/chirps//20110924.tif"
[117] "data/chirps//20110925.tif" "data/chirps//20110926.tif"
[119] "data/chirps//20110927.tif" "data/chirps//20110928.tif"
[121] "data/chirps//20110929.tif" "data/chirps//20110930.tif"

$`2012`
  [1] "data/chirps//20120601.tif" "data/chirps//20120602.tif"
  [3] "data/chirps//20120603.tif" "data/chirps//20120604.tif"
  [5] "data/chirps//20120605.tif" "data/chirps//20120606.tif"
  [7] "data/chirps//20120607.tif" "data/chirps//20120608.tif"
  [9] "data/chirps//20120609.tif" "data/chirps//20120610.tif"
 [11] "data/chirps//20120611.tif" "data/chirps//20120612.tif"
 [13] "data/chirps//20120613.tif" "data/chirps//20120614.tif"
 [15] "data/chirps//20120615.tif" "data/chirps//20120616.tif"
 [17] "data/chirps//20120617.tif" "data/chirps//20120618.tif"
 [19] "data/chirps//20120619.tif" "data/chirps//20120620.tif"
 [21] "data/chirps//20120621.tif" "data/chirps//20120622.tif"
 [23] "data/chirps//20120623.tif" "data/chirps//20120624.tif"
 [25] "data/chirps//20120625.tif" "data/chirps//20120626.tif"
 [27] "data/chirps//20120627.tif" "data/chirps//20120628.tif"
 [29] "data/chirps//20120629.tif" "data/chirps//20120630.tif"
 [31] "data/chirps//20120701.tif" "data/chirps//20120702.tif"
 [33] "data/chirps//20120703.tif" "data/chirps//20120704.tif"
 [35] "data/chirps//20120705.tif" "data/chirps//20120706.tif"
 [37] "data/chirps//20120707.tif" "data/chirps//20120708.tif"
 [39] "data/chirps//20120709.tif" "data/chirps//20120710.tif"
 [41] "data/chirps//20120711.tif" "data/chirps//20120712.tif"
 [43] "data/chirps//20120713.tif" "data/chirps//20120714.tif"
 [45] "data/chirps//20120715.tif" "data/chirps//20120716.tif"
 [47] "data/chirps//20120717.tif" "data/chirps//20120718.tif"
 [49] "data/chirps//20120719.tif" "data/chirps//20120720.tif"
 [51] "data/chirps//20120721.tif" "data/chirps//20120722.tif"
 [53] "data/chirps//20120723.tif" "data/chirps//20120724.tif"
 [55] "data/chirps//20120725.tif" "data/chirps//20120726.tif"
 [57] "data/chirps//20120727.tif" "data/chirps//20120728.tif"
 [59] "data/chirps//20120729.tif" "data/chirps//20120730.tif"
 [61] "data/chirps//20120731.tif" "data/chirps//20120801.tif"
 [63] "data/chirps//20120802.tif" "data/chirps//20120803.tif"
 [65] "data/chirps//20120804.tif" "data/chirps//20120805.tif"
 [67] "data/chirps//20120806.tif" "data/chirps//20120807.tif"
 [69] "data/chirps//20120808.tif" "data/chirps//20120809.tif"
 [71] "data/chirps//20120810.tif" "data/chirps//20120811.tif"
 [73] "data/chirps//20120812.tif" "data/chirps//20120813.tif"
 [75] "data/chirps//20120814.tif" "data/chirps//20120815.tif"
 [77] "data/chirps//20120816.tif" "data/chirps//20120817.tif"
 [79] "data/chirps//20120818.tif" "data/chirps//20120819.tif"
 [81] "data/chirps//20120820.tif" "data/chirps//20120821.tif"
 [83] "data/chirps//20120822.tif" "data/chirps//20120823.tif"
 [85] "data/chirps//20120824.tif" "data/chirps//20120825.tif"
 [87] "data/chirps//20120826.tif" "data/chirps//20120827.tif"
 [89] "data/chirps//20120828.tif" "data/chirps//20120829.tif"
 [91] "data/chirps//20120830.tif" "data/chirps//20120831.tif"
 [93] "data/chirps//20120901.tif" "data/chirps//20120902.tif"
 [95] "data/chirps//20120903.tif" "data/chirps//20120904.tif"
 [97] "data/chirps//20120905.tif" "data/chirps//20120906.tif"
 [99] "data/chirps//20120907.tif" "data/chirps//20120908.tif"
[101] "data/chirps//20120909.tif" "data/chirps//20120910.tif"
[103] "data/chirps//20120911.tif" "data/chirps//20120912.tif"
[105] "data/chirps//20120913.tif" "data/chirps//20120914.tif"
[107] "data/chirps//20120915.tif" "data/chirps//20120916.tif"
[109] "data/chirps//20120917.tif" "data/chirps//20120918.tif"
[111] "data/chirps//20120919.tif" "data/chirps//20120920.tif"
[113] "data/chirps//20120921.tif" "data/chirps//20120922.tif"
[115] "data/chirps//20120923.tif" "data/chirps//20120924.tif"
[117] "data/chirps//20120925.tif" "data/chirps//20120926.tif"
[119] "data/chirps//20120927.tif" "data/chirps//20120928.tif"
[121] "data/chirps//20120929.tif" "data/chirps//20120930.tif"

$`2013`
  [1] "data/chirps//20130601.tif" "data/chirps//20130602.tif"
  [3] "data/chirps//20130603.tif" "data/chirps//20130604.tif"
  [5] "data/chirps//20130605.tif" "data/chirps//20130606.tif"
  [7] "data/chirps//20130607.tif" "data/chirps//20130608.tif"
  [9] "data/chirps//20130609.tif" "data/chirps//20130610.tif"
 [11] "data/chirps//20130611.tif" "data/chirps//20130612.tif"
 [13] "data/chirps//20130613.tif" "data/chirps//20130614.tif"
 [15] "data/chirps//20130615.tif" "data/chirps//20130616.tif"
 [17] "data/chirps//20130617.tif" "data/chirps//20130618.tif"
 [19] "data/chirps//20130619.tif" "data/chirps//20130620.tif"
 [21] "data/chirps//20130621.tif" "data/chirps//20130622.tif"
 [23] "data/chirps//20130623.tif" "data/chirps//20130624.tif"
 [25] "data/chirps//20130625.tif" "data/chirps//20130626.tif"
 [27] "data/chirps//20130627.tif" "data/chirps//20130628.tif"
 [29] "data/chirps//20130629.tif" "data/chirps//20130630.tif"
 [31] "data/chirps//20130701.tif" "data/chirps//20130702.tif"
 [33] "data/chirps//20130703.tif" "data/chirps//20130704.tif"
 [35] "data/chirps//20130705.tif" "data/chirps//20130706.tif"
 [37] "data/chirps//20130707.tif" "data/chirps//20130708.tif"
 [39] "data/chirps//20130709.tif" "data/chirps//20130710.tif"
 [41] "data/chirps//20130711.tif" "data/chirps//20130712.tif"
 [43] "data/chirps//20130713.tif" "data/chirps//20130714.tif"
 [45] "data/chirps//20130715.tif" "data/chirps//20130716.tif"
 [47] "data/chirps//20130717.tif" "data/chirps//20130718.tif"
 [49] "data/chirps//20130719.tif" "data/chirps//20130720.tif"
 [51] "data/chirps//20130721.tif" "data/chirps//20130722.tif"
 [53] "data/chirps//20130723.tif" "data/chirps//20130724.tif"
 [55] "data/chirps//20130725.tif" "data/chirps//20130726.tif"
 [57] "data/chirps//20130727.tif" "data/chirps//20130728.tif"
 [59] "data/chirps//20130729.tif" "data/chirps//20130730.tif"
 [61] "data/chirps//20130731.tif" "data/chirps//20130801.tif"
 [63] "data/chirps//20130802.tif" "data/chirps//20130803.tif"
 [65] "data/chirps//20130804.tif" "data/chirps//20130805.tif"
 [67] "data/chirps//20130806.tif" "data/chirps//20130807.tif"
 [69] "data/chirps//20130808.tif" "data/chirps//20130809.tif"
 [71] "data/chirps//20130810.tif" "data/chirps//20130811.tif"
 [73] "data/chirps//20130812.tif" "data/chirps//20130813.tif"
 [75] "data/chirps//20130814.tif" "data/chirps//20130815.tif"
 [77] "data/chirps//20130816.tif" "data/chirps//20130817.tif"
 [79] "data/chirps//20130818.tif" "data/chirps//20130819.tif"
 [81] "data/chirps//20130820.tif" "data/chirps//20130821.tif"
 [83] "data/chirps//20130822.tif" "data/chirps//20130823.tif"
 [85] "data/chirps//20130824.tif" "data/chirps//20130825.tif"
 [87] "data/chirps//20130826.tif" "data/chirps//20130827.tif"
 [89] "data/chirps//20130828.tif" "data/chirps//20130829.tif"
 [91] "data/chirps//20130830.tif" "data/chirps//20130831.tif"
 [93] "data/chirps//20130901.tif" "data/chirps//20130902.tif"
 [95] "data/chirps//20130903.tif" "data/chirps//20130904.tif"
 [97] "data/chirps//20130905.tif" "data/chirps//20130906.tif"
 [99] "data/chirps//20130907.tif" "data/chirps//20130908.tif"
[101] "data/chirps//20130909.tif" "data/chirps//20130910.tif"
[103] "data/chirps//20130911.tif" "data/chirps//20130912.tif"
[105] "data/chirps//20130913.tif" "data/chirps//20130914.tif"
[107] "data/chirps//20130915.tif" "data/chirps//20130916.tif"
[109] "data/chirps//20130917.tif" "data/chirps//20130918.tif"
[111] "data/chirps//20130919.tif" "data/chirps//20130920.tif"
[113] "data/chirps//20130921.tif" "data/chirps//20130922.tif"
[115] "data/chirps//20130923.tif" "data/chirps//20130924.tif"
[117] "data/chirps//20130925.tif" "data/chirps//20130926.tif"
[119] "data/chirps//20130927.tif" "data/chirps//20130928.tif"
[121] "data/chirps//20130929.tif" "data/chirps//20130930.tif"

$`2014`
  [1] "data/chirps//20140601.tif" "data/chirps//20140602.tif"
  [3] "data/chirps//20140603.tif" "data/chirps//20140604.tif"
  [5] "data/chirps//20140605.tif" "data/chirps//20140606.tif"
  [7] "data/chirps//20140607.tif" "data/chirps//20140608.tif"
  [9] "data/chirps//20140609.tif" "data/chirps//20140610.tif"
 [11] "data/chirps//20140611.tif" "data/chirps//20140612.tif"
 [13] "data/chirps//20140613.tif" "data/chirps//20140614.tif"
 [15] "data/chirps//20140615.tif" "data/chirps//20140616.tif"
 [17] "data/chirps//20140617.tif" "data/chirps//20140618.tif"
 [19] "data/chirps//20140619.tif" "data/chirps//20140620.tif"
 [21] "data/chirps//20140621.tif" "data/chirps//20140622.tif"
 [23] "data/chirps//20140623.tif" "data/chirps//20140624.tif"
 [25] "data/chirps//20140625.tif" "data/chirps//20140626.tif"
 [27] "data/chirps//20140627.tif" "data/chirps//20140628.tif"
 [29] "data/chirps//20140629.tif" "data/chirps//20140630.tif"
 [31] "data/chirps//20140701.tif" "data/chirps//20140702.tif"
 [33] "data/chirps//20140703.tif" "data/chirps//20140704.tif"
 [35] "data/chirps//20140705.tif" "data/chirps//20140706.tif"
 [37] "data/chirps//20140707.tif" "data/chirps//20140708.tif"
 [39] "data/chirps//20140709.tif" "data/chirps//20140710.tif"
 [41] "data/chirps//20140711.tif" "data/chirps//20140712.tif"
 [43] "data/chirps//20140713.tif" "data/chirps//20140714.tif"
 [45] "data/chirps//20140715.tif" "data/chirps//20140716.tif"
 [47] "data/chirps//20140717.tif" "data/chirps//20140718.tif"
 [49] "data/chirps//20140719.tif" "data/chirps//20140720.tif"
 [51] "data/chirps//20140721.tif" "data/chirps//20140722.tif"
 [53] "data/chirps//20140723.tif" "data/chirps//20140724.tif"
 [55] "data/chirps//20140725.tif" "data/chirps//20140726.tif"
 [57] "data/chirps//20140727.tif" "data/chirps//20140728.tif"
 [59] "data/chirps//20140729.tif" "data/chirps//20140730.tif"
 [61] "data/chirps//20140731.tif" "data/chirps//20140801.tif"
 [63] "data/chirps//20140802.tif" "data/chirps//20140803.tif"
 [65] "data/chirps//20140804.tif" "data/chirps//20140805.tif"
 [67] "data/chirps//20140806.tif" "data/chirps//20140807.tif"
 [69] "data/chirps//20140808.tif" "data/chirps//20140809.tif"
 [71] "data/chirps//20140810.tif" "data/chirps//20140811.tif"
 [73] "data/chirps//20140812.tif" "data/chirps//20140813.tif"
 [75] "data/chirps//20140814.tif" "data/chirps//20140815.tif"
 [77] "data/chirps//20140816.tif" "data/chirps//20140817.tif"
 [79] "data/chirps//20140818.tif" "data/chirps//20140819.tif"
 [81] "data/chirps//20140820.tif" "data/chirps//20140821.tif"
 [83] "data/chirps//20140822.tif" "data/chirps//20140823.tif"
 [85] "data/chirps//20140824.tif" "data/chirps//20140825.tif"
 [87] "data/chirps//20140826.tif" "data/chirps//20140827.tif"
 [89] "data/chirps//20140828.tif" "data/chirps//20140829.tif"
 [91] "data/chirps//20140830.tif" "data/chirps//20140831.tif"
 [93] "data/chirps//20140901.tif" "data/chirps//20140902.tif"
 [95] "data/chirps//20140903.tif" "data/chirps//20140904.tif"
 [97] "data/chirps//20140905.tif" "data/chirps//20140906.tif"
 [99] "data/chirps//20140907.tif" "data/chirps//20140908.tif"
[101] "data/chirps//20140909.tif" "data/chirps//20140910.tif"
[103] "data/chirps//20140911.tif" "data/chirps//20140912.tif"
[105] "data/chirps//20140913.tif" "data/chirps//20140914.tif"
[107] "data/chirps//20140915.tif" "data/chirps//20140916.tif"
[109] "data/chirps//20140917.tif" "data/chirps//20140918.tif"
[111] "data/chirps//20140919.tif" "data/chirps//20140920.tif"
[113] "data/chirps//20140921.tif" "data/chirps//20140922.tif"
[115] "data/chirps//20140923.tif" "data/chirps//20140924.tif"
[117] "data/chirps//20140925.tif" "data/chirps//20140926.tif"
[119] "data/chirps//20140927.tif" "data/chirps//20140928.tif"
[121] "data/chirps//20140929.tif" "data/chirps//20140930.tif"

$`2015`
  [1] "data/chirps//20150601.tif" "data/chirps//20150602.tif"
  [3] "data/chirps//20150603.tif" "data/chirps//20150604.tif"
  [5] "data/chirps//20150605.tif" "data/chirps//20150606.tif"
  [7] "data/chirps//20150607.tif" "data/chirps//20150608.tif"
  [9] "data/chirps//20150609.tif" "data/chirps//20150610.tif"
 [11] "data/chirps//20150611.tif" "data/chirps//20150612.tif"
 [13] "data/chirps//20150613.tif" "data/chirps//20150614.tif"
 [15] "data/chirps//20150615.tif" "data/chirps//20150616.tif"
 [17] "data/chirps//20150617.tif" "data/chirps//20150618.tif"
 [19] "data/chirps//20150619.tif" "data/chirps//20150620.tif"
 [21] "data/chirps//20150621.tif" "data/chirps//20150622.tif"
 [23] "data/chirps//20150623.tif" "data/chirps//20150624.tif"
 [25] "data/chirps//20150625.tif" "data/chirps//20150626.tif"
 [27] "data/chirps//20150627.tif" "data/chirps//20150628.tif"
 [29] "data/chirps//20150629.tif" "data/chirps//20150630.tif"
 [31] "data/chirps//20150701.tif" "data/chirps//20150702.tif"
 [33] "data/chirps//20150703.tif" "data/chirps//20150704.tif"
 [35] "data/chirps//20150705.tif" "data/chirps//20150706.tif"
 [37] "data/chirps//20150707.tif" "data/chirps//20150708.tif"
 [39] "data/chirps//20150709.tif" "data/chirps//20150710.tif"
 [41] "data/chirps//20150711.tif" "data/chirps//20150712.tif"
 [43] "data/chirps//20150713.tif" "data/chirps//20150714.tif"
 [45] "data/chirps//20150715.tif" "data/chirps//20150716.tif"
 [47] "data/chirps//20150717.tif" "data/chirps//20150718.tif"
 [49] "data/chirps//20150719.tif" "data/chirps//20150720.tif"
 [51] "data/chirps//20150721.tif" "data/chirps//20150722.tif"
 [53] "data/chirps//20150723.tif" "data/chirps//20150724.tif"
 [55] "data/chirps//20150725.tif" "data/chirps//20150726.tif"
 [57] "data/chirps//20150727.tif" "data/chirps//20150728.tif"
 [59] "data/chirps//20150729.tif" "data/chirps//20150730.tif"
 [61] "data/chirps//20150731.tif" "data/chirps//20150801.tif"
 [63] "data/chirps//20150802.tif" "data/chirps//20150803.tif"
 [65] "data/chirps//20150804.tif" "data/chirps//20150805.tif"
 [67] "data/chirps//20150806.tif" "data/chirps//20150807.tif"
 [69] "data/chirps//20150808.tif" "data/chirps//20150809.tif"
 [71] "data/chirps//20150810.tif" "data/chirps//20150811.tif"
 [73] "data/chirps//20150812.tif" "data/chirps//20150813.tif"
 [75] "data/chirps//20150814.tif" "data/chirps//20150815.tif"
 [77] "data/chirps//20150816.tif" "data/chirps//20150817.tif"
 [79] "data/chirps//20150818.tif" "data/chirps//20150819.tif"
 [81] "data/chirps//20150820.tif" "data/chirps//20150821.tif"
 [83] "data/chirps//20150822.tif" "data/chirps//20150823.tif"
 [85] "data/chirps//20150824.tif" "data/chirps//20150825.tif"
 [87] "data/chirps//20150826.tif" "data/chirps//20150827.tif"
 [89] "data/chirps//20150828.tif" "data/chirps//20150829.tif"
 [91] "data/chirps//20150830.tif" "data/chirps//20150831.tif"
 [93] "data/chirps//20150901.tif" "data/chirps//20150902.tif"
 [95] "data/chirps//20150903.tif" "data/chirps//20150904.tif"
 [97] "data/chirps//20150905.tif" "data/chirps//20150906.tif"
 [99] "data/chirps//20150907.tif" "data/chirps//20150908.tif"
[101] "data/chirps//20150909.tif" "data/chirps//20150910.tif"
[103] "data/chirps//20150911.tif" "data/chirps//20150912.tif"
[105] "data/chirps//20150913.tif" "data/chirps//20150914.tif"
[107] "data/chirps//20150915.tif" "data/chirps//20150916.tif"
[109] "data/chirps//20150917.tif" "data/chirps//20150918.tif"
[111] "data/chirps//20150919.tif" "data/chirps//20150920.tif"
[113] "data/chirps//20150921.tif" "data/chirps//20150922.tif"
[115] "data/chirps//20150923.tif" "data/chirps//20150924.tif"
[117] "data/chirps//20150925.tif" "data/chirps//20150926.tif"
[119] "data/chirps//20150927.tif" "data/chirps//20150928.tif"
[121] "data/chirps//20150929.tif" "data/chirps//20150930.tif"

$`2016`
  [1] "data/chirps//20160601.tif" "data/chirps//20160602.tif"
  [3] "data/chirps//20160603.tif" "data/chirps//20160604.tif"
  [5] "data/chirps//20160605.tif" "data/chirps//20160606.tif"
  [7] "data/chirps//20160607.tif" "data/chirps//20160608.tif"
  [9] "data/chirps//20160609.tif" "data/chirps//20160610.tif"
 [11] "data/chirps//20160611.tif" "data/chirps//20160612.tif"
 [13] "data/chirps//20160613.tif" "data/chirps//20160614.tif"
 [15] "data/chirps//20160615.tif" "data/chirps//20160616.tif"
 [17] "data/chirps//20160617.tif" "data/chirps//20160618.tif"
 [19] "data/chirps//20160619.tif" "data/chirps//20160620.tif"
 [21] "data/chirps//20160621.tif" "data/chirps//20160622.tif"
 [23] "data/chirps//20160623.tif" "data/chirps//20160624.tif"
 [25] "data/chirps//20160625.tif" "data/chirps//20160626.tif"
 [27] "data/chirps//20160627.tif" "data/chirps//20160628.tif"
 [29] "data/chirps//20160629.tif" "data/chirps//20160630.tif"
 [31] "data/chirps//20160701.tif" "data/chirps//20160702.tif"
 [33] "data/chirps//20160703.tif" "data/chirps//20160704.tif"
 [35] "data/chirps//20160705.tif" "data/chirps//20160706.tif"
 [37] "data/chirps//20160707.tif" "data/chirps//20160708.tif"
 [39] "data/chirps//20160709.tif" "data/chirps//20160710.tif"
 [41] "data/chirps//20160711.tif" "data/chirps//20160712.tif"
 [43] "data/chirps//20160713.tif" "data/chirps//20160714.tif"
 [45] "data/chirps//20160715.tif" "data/chirps//20160716.tif"
 [47] "data/chirps//20160717.tif" "data/chirps//20160718.tif"
 [49] "data/chirps//20160719.tif" "data/chirps//20160720.tif"
 [51] "data/chirps//20160721.tif" "data/chirps//20160722.tif"
 [53] "data/chirps//20160723.tif" "data/chirps//20160724.tif"
 [55] "data/chirps//20160725.tif" "data/chirps//20160726.tif"
 [57] "data/chirps//20160727.tif" "data/chirps//20160728.tif"
 [59] "data/chirps//20160729.tif" "data/chirps//20160730.tif"
 [61] "data/chirps//20160731.tif" "data/chirps//20160801.tif"
 [63] "data/chirps//20160802.tif" "data/chirps//20160803.tif"
 [65] "data/chirps//20160804.tif" "data/chirps//20160805.tif"
 [67] "data/chirps//20160806.tif" "data/chirps//20160807.tif"
 [69] "data/chirps//20160808.tif" "data/chirps//20160809.tif"
 [71] "data/chirps//20160810.tif" "data/chirps//20160811.tif"
 [73] "data/chirps//20160812.tif" "data/chirps//20160813.tif"
 [75] "data/chirps//20160814.tif" "data/chirps//20160815.tif"
 [77] "data/chirps//20160816.tif" "data/chirps//20160817.tif"
 [79] "data/chirps//20160818.tif" "data/chirps//20160819.tif"
 [81] "data/chirps//20160820.tif" "data/chirps//20160821.tif"
 [83] "data/chirps//20160822.tif" "data/chirps//20160823.tif"
 [85] "data/chirps//20160824.tif" "data/chirps//20160825.tif"
 [87] "data/chirps//20160826.tif" "data/chirps//20160827.tif"
 [89] "data/chirps//20160828.tif" "data/chirps//20160829.tif"
 [91] "data/chirps//20160830.tif" "data/chirps//20160831.tif"
 [93] "data/chirps//20160901.tif" "data/chirps//20160902.tif"
 [95] "data/chirps//20160903.tif" "data/chirps//20160904.tif"
 [97] "data/chirps//20160905.tif" "data/chirps//20160906.tif"
 [99] "data/chirps//20160907.tif" "data/chirps//20160908.tif"
[101] "data/chirps//20160909.tif" "data/chirps//20160910.tif"
[103] "data/chirps//20160911.tif" "data/chirps//20160912.tif"
[105] "data/chirps//20160913.tif" "data/chirps//20160914.tif"
[107] "data/chirps//20160915.tif" "data/chirps//20160916.tif"
[109] "data/chirps//20160917.tif" "data/chirps//20160918.tif"
[111] "data/chirps//20160919.tif" "data/chirps//20160920.tif"
[113] "data/chirps//20160921.tif" "data/chirps//20160922.tif"
[115] "data/chirps//20160923.tif" "data/chirps//20160924.tif"
[117] "data/chirps//20160925.tif" "data/chirps//20160926.tif"
[119] "data/chirps//20160927.tif" "data/chirps//20160928.tif"
[121] "data/chirps//20160929.tif" "data/chirps//20160930.tif"

$`2017`
  [1] "data/chirps//20170601.tif" "data/chirps//20170602.tif"
  [3] "data/chirps//20170603.tif" "data/chirps//20170604.tif"
  [5] "data/chirps//20170605.tif" "data/chirps//20170606.tif"
  [7] "data/chirps//20170607.tif" "data/chirps//20170608.tif"
  [9] "data/chirps//20170609.tif" "data/chirps//20170610.tif"
 [11] "data/chirps//20170611.tif" "data/chirps//20170612.tif"
 [13] "data/chirps//20170613.tif" "data/chirps//20170614.tif"
 [15] "data/chirps//20170615.tif" "data/chirps//20170616.tif"
 [17] "data/chirps//20170617.tif" "data/chirps//20170618.tif"
 [19] "data/chirps//20170619.tif" "data/chirps//20170620.tif"
 [21] "data/chirps//20170621.tif" "data/chirps//20170622.tif"
 [23] "data/chirps//20170623.tif" "data/chirps//20170624.tif"
 [25] "data/chirps//20170625.tif" "data/chirps//20170626.tif"
 [27] "data/chirps//20170627.tif" "data/chirps//20170628.tif"
 [29] "data/chirps//20170629.tif" "data/chirps//20170630.tif"
 [31] "data/chirps//20170701.tif" "data/chirps//20170702.tif"
 [33] "data/chirps//20170703.tif" "data/chirps//20170704.tif"
 [35] "data/chirps//20170705.tif" "data/chirps//20170706.tif"
 [37] "data/chirps//20170707.tif" "data/chirps//20170708.tif"
 [39] "data/chirps//20170709.tif" "data/chirps//20170710.tif"
 [41] "data/chirps//20170711.tif" "data/chirps//20170712.tif"
 [43] "data/chirps//20170713.tif" "data/chirps//20170714.tif"
 [45] "data/chirps//20170715.tif" "data/chirps//20170716.tif"
 [47] "data/chirps//20170717.tif" "data/chirps//20170718.tif"
 [49] "data/chirps//20170719.tif" "data/chirps//20170720.tif"
 [51] "data/chirps//20170721.tif" "data/chirps//20170722.tif"
 [53] "data/chirps//20170723.tif" "data/chirps//20170724.tif"
 [55] "data/chirps//20170725.tif" "data/chirps//20170726.tif"
 [57] "data/chirps//20170727.tif" "data/chirps//20170728.tif"
 [59] "data/chirps//20170729.tif" "data/chirps//20170730.tif"
 [61] "data/chirps//20170731.tif" "data/chirps//20170801.tif"
 [63] "data/chirps//20170802.tif" "data/chirps//20170803.tif"
 [65] "data/chirps//20170804.tif" "data/chirps//20170805.tif"
 [67] "data/chirps//20170806.tif" "data/chirps//20170807.tif"
 [69] "data/chirps//20170808.tif" "data/chirps//20170809.tif"
 [71] "data/chirps//20170810.tif" "data/chirps//20170811.tif"
 [73] "data/chirps//20170812.tif" "data/chirps//20170813.tif"
 [75] "data/chirps//20170814.tif" "data/chirps//20170815.tif"
 [77] "data/chirps//20170816.tif" "data/chirps//20170817.tif"
 [79] "data/chirps//20170818.tif" "data/chirps//20170819.tif"
 [81] "data/chirps//20170820.tif" "data/chirps//20170821.tif"
 [83] "data/chirps//20170822.tif" "data/chirps//20170823.tif"
 [85] "data/chirps//20170824.tif" "data/chirps//20170825.tif"
 [87] "data/chirps//20170826.tif" "data/chirps//20170827.tif"
 [89] "data/chirps//20170828.tif" "data/chirps//20170829.tif"
 [91] "data/chirps//20170830.tif" "data/chirps//20170831.tif"
 [93] "data/chirps//20170901.tif" "data/chirps//20170902.tif"
 [95] "data/chirps//20170903.tif" "data/chirps//20170904.tif"
 [97] "data/chirps//20170905.tif" "data/chirps//20170906.tif"
 [99] "data/chirps//20170907.tif" "data/chirps//20170908.tif"
[101] "data/chirps//20170909.tif" "data/chirps//20170910.tif"
[103] "data/chirps//20170911.tif" "data/chirps//20170912.tif"
[105] "data/chirps//20170913.tif" "data/chirps//20170914.tif"
[107] "data/chirps//20170915.tif" "data/chirps//20170916.tif"
[109] "data/chirps//20170917.tif" "data/chirps//20170918.tif"
[111] "data/chirps//20170919.tif" "data/chirps//20170920.tif"
[113] "data/chirps//20170921.tif" "data/chirps//20170922.tif"
[115] "data/chirps//20170923.tif" "data/chirps//20170924.tif"
[117] "data/chirps//20170925.tif" "data/chirps//20170926.tif"
[119] "data/chirps//20170927.tif" "data/chirps//20170928.tif"
[121] "data/chirps//20170929.tif" "data/chirps//20170930.tif"

$`2018`
  [1] "data/chirps//20180601.tif" "data/chirps//20180602.tif"
  [3] "data/chirps//20180603.tif" "data/chirps//20180604.tif"
  [5] "data/chirps//20180605.tif" "data/chirps//20180606.tif"
  [7] "data/chirps//20180607.tif" "data/chirps//20180608.tif"
  [9] "data/chirps//20180609.tif" "data/chirps//20180610.tif"
 [11] "data/chirps//20180611.tif" "data/chirps//20180612.tif"
 [13] "data/chirps//20180613.tif" "data/chirps//20180614.tif"
 [15] "data/chirps//20180615.tif" "data/chirps//20180616.tif"
 [17] "data/chirps//20180617.tif" "data/chirps//20180618.tif"
 [19] "data/chirps//20180619.tif" "data/chirps//20180620.tif"
 [21] "data/chirps//20180621.tif" "data/chirps//20180622.tif"
 [23] "data/chirps//20180623.tif" "data/chirps//20180624.tif"
 [25] "data/chirps//20180625.tif" "data/chirps//20180626.tif"
 [27] "data/chirps//20180627.tif" "data/chirps//20180628.tif"
 [29] "data/chirps//20180629.tif" "data/chirps//20180630.tif"
 [31] "data/chirps//20180701.tif" "data/chirps//20180702.tif"
 [33] "data/chirps//20180703.tif" "data/chirps//20180704.tif"
 [35] "data/chirps//20180705.tif" "data/chirps//20180706.tif"
 [37] "data/chirps//20180707.tif" "data/chirps//20180708.tif"
 [39] "data/chirps//20180709.tif" "data/chirps//20180710.tif"
 [41] "data/chirps//20180711.tif" "data/chirps//20180712.tif"
 [43] "data/chirps//20180713.tif" "data/chirps//20180714.tif"
 [45] "data/chirps//20180715.tif" "data/chirps//20180716.tif"
 [47] "data/chirps//20180717.tif" "data/chirps//20180718.tif"
 [49] "data/chirps//20180719.tif" "data/chirps//20180720.tif"
 [51] "data/chirps//20180721.tif" "data/chirps//20180722.tif"
 [53] "data/chirps//20180723.tif" "data/chirps//20180724.tif"
 [55] "data/chirps//20180725.tif" "data/chirps//20180726.tif"
 [57] "data/chirps//20180727.tif" "data/chirps//20180728.tif"
 [59] "data/chirps//20180729.tif" "data/chirps//20180730.tif"
 [61] "data/chirps//20180731.tif" "data/chirps//20180801.tif"
 [63] "data/chirps//20180802.tif" "data/chirps//20180803.tif"
 [65] "data/chirps//20180804.tif" "data/chirps//20180805.tif"
 [67] "data/chirps//20180806.tif" "data/chirps//20180807.tif"
 [69] "data/chirps//20180808.tif" "data/chirps//20180809.tif"
 [71] "data/chirps//20180810.tif" "data/chirps//20180811.tif"
 [73] "data/chirps//20180812.tif" "data/chirps//20180813.tif"
 [75] "data/chirps//20180814.tif" "data/chirps//20180815.tif"
 [77] "data/chirps//20180816.tif" "data/chirps//20180817.tif"
 [79] "data/chirps//20180818.tif" "data/chirps//20180819.tif"
 [81] "data/chirps//20180820.tif" "data/chirps//20180821.tif"
 [83] "data/chirps//20180822.tif" "data/chirps//20180823.tif"
 [85] "data/chirps//20180824.tif" "data/chirps//20180825.tif"
 [87] "data/chirps//20180826.tif" "data/chirps//20180827.tif"
 [89] "data/chirps//20180828.tif" "data/chirps//20180829.tif"
 [91] "data/chirps//20180830.tif" "data/chirps//20180831.tif"
 [93] "data/chirps//20180901.tif" "data/chirps//20180902.tif"
 [95] "data/chirps//20180903.tif" "data/chirps//20180904.tif"
 [97] "data/chirps//20180905.tif" "data/chirps//20180906.tif"
 [99] "data/chirps//20180907.tif" "data/chirps//20180908.tif"
[101] "data/chirps//20180909.tif" "data/chirps//20180910.tif"
[103] "data/chirps//20180911.tif" "data/chirps//20180912.tif"
[105] "data/chirps//20180913.tif" "data/chirps//20180914.tif"
[107] "data/chirps//20180915.tif" "data/chirps//20180916.tif"
[109] "data/chirps//20180917.tif" "data/chirps//20180918.tif"
[111] "data/chirps//20180919.tif" "data/chirps//20180920.tif"
[113] "data/chirps//20180921.tif" "data/chirps//20180922.tif"
[115] "data/chirps//20180923.tif" "data/chirps//20180924.tif"
[117] "data/chirps//20180925.tif" "data/chirps//20180926.tif"
[119] "data/chirps//20180927.tif" "data/chirps//20180928.tif"
[121] "data/chirps//20180929.tif" "data/chirps//20180930.tif"

$`2019`
  [1] "data/chirps//20190601.tif" "data/chirps//20190602.tif"
  [3] "data/chirps//20190603.tif" "data/chirps//20190604.tif"
  [5] "data/chirps//20190605.tif" "data/chirps//20190606.tif"
  [7] "data/chirps//20190607.tif" "data/chirps//20190608.tif"
  [9] "data/chirps//20190609.tif" "data/chirps//20190610.tif"
 [11] "data/chirps//20190611.tif" "data/chirps//20190612.tif"
 [13] "data/chirps//20190613.tif" "data/chirps//20190614.tif"
 [15] "data/chirps//20190615.tif" "data/chirps//20190616.tif"
 [17] "data/chirps//20190617.tif" "data/chirps//20190618.tif"
 [19] "data/chirps//20190619.tif" "data/chirps//20190620.tif"
 [21] "data/chirps//20190621.tif" "data/chirps//20190622.tif"
 [23] "data/chirps//20190623.tif" "data/chirps//20190624.tif"
 [25] "data/chirps//20190625.tif" "data/chirps//20190626.tif"
 [27] "data/chirps//20190627.tif" "data/chirps//20190628.tif"
 [29] "data/chirps//20190629.tif" "data/chirps//20190630.tif"
 [31] "data/chirps//20190701.tif" "data/chirps//20190702.tif"
 [33] "data/chirps//20190703.tif" "data/chirps//20190704.tif"
 [35] "data/chirps//20190705.tif" "data/chirps//20190706.tif"
 [37] "data/chirps//20190707.tif" "data/chirps//20190708.tif"
 [39] "data/chirps//20190709.tif" "data/chirps//20190710.tif"
 [41] "data/chirps//20190711.tif" "data/chirps//20190712.tif"
 [43] "data/chirps//20190713.tif" "data/chirps//20190714.tif"
 [45] "data/chirps//20190715.tif" "data/chirps//20190716.tif"
 [47] "data/chirps//20190717.tif" "data/chirps//20190718.tif"
 [49] "data/chirps//20190719.tif" "data/chirps//20190720.tif"
 [51] "data/chirps//20190721.tif" "data/chirps//20190722.tif"
 [53] "data/chirps//20190723.tif" "data/chirps//20190724.tif"
 [55] "data/chirps//20190725.tif" "data/chirps//20190726.tif"
 [57] "data/chirps//20190727.tif" "data/chirps//20190728.tif"
 [59] "data/chirps//20190729.tif" "data/chirps//20190730.tif"
 [61] "data/chirps//20190731.tif" "data/chirps//20190801.tif"
 [63] "data/chirps//20190802.tif" "data/chirps//20190803.tif"
 [65] "data/chirps//20190804.tif" "data/chirps//20190805.tif"
 [67] "data/chirps//20190806.tif" "data/chirps//20190807.tif"
 [69] "data/chirps//20190808.tif" "data/chirps//20190809.tif"
 [71] "data/chirps//20190810.tif" "data/chirps//20190811.tif"
 [73] "data/chirps//20190812.tif" "data/chirps//20190813.tif"
 [75] "data/chirps//20190814.tif" "data/chirps//20190815.tif"
 [77] "data/chirps//20190816.tif" "data/chirps//20190817.tif"
 [79] "data/chirps//20190818.tif" "data/chirps//20190819.tif"
 [81] "data/chirps//20190820.tif" "data/chirps//20190821.tif"
 [83] "data/chirps//20190822.tif" "data/chirps//20190823.tif"
 [85] "data/chirps//20190824.tif" "data/chirps//20190825.tif"
 [87] "data/chirps//20190826.tif" "data/chirps//20190827.tif"
 [89] "data/chirps//20190828.tif" "data/chirps//20190829.tif"
 [91] "data/chirps//20190830.tif" "data/chirps//20190831.tif"
 [93] "data/chirps//20190901.tif" "data/chirps//20190902.tif"
 [95] "data/chirps//20190903.tif" "data/chirps//20190904.tif"
 [97] "data/chirps//20190905.tif" "data/chirps//20190906.tif"
 [99] "data/chirps//20190907.tif" "data/chirps//20190908.tif"
[101] "data/chirps//20190909.tif" "data/chirps//20190910.tif"
[103] "data/chirps//20190911.tif" "data/chirps//20190912.tif"
[105] "data/chirps//20190913.tif" "data/chirps//20190914.tif"
[107] "data/chirps//20190915.tif" "data/chirps//20190916.tif"
[109] "data/chirps//20190917.tif" "data/chirps//20190918.tif"
[111] "data/chirps//20190919.tif" "data/chirps//20190920.tif"
[113] "data/chirps//20190921.tif" "data/chirps//20190922.tif"
[115] "data/chirps//20190923.tif" "data/chirps//20190924.tif"
[117] "data/chirps//20190925.tif" "data/chirps//20190926.tif"
[119] "data/chirps//20190927.tif" "data/chirps//20190928.tif"
[121] "data/chirps//20190929.tif" "data/chirps//20190930.tif"

$`2020`
  [1] "data/chirps//20200601.tif" "data/chirps//20200602.tif"
  [3] "data/chirps//20200603.tif" "data/chirps//20200604.tif"
  [5] "data/chirps//20200605.tif" "data/chirps//20200606.tif"
  [7] "data/chirps//20200607.tif" "data/chirps//20200608.tif"
  [9] "data/chirps//20200609.tif" "data/chirps//20200610.tif"
 [11] "data/chirps//20200611.tif" "data/chirps//20200612.tif"
 [13] "data/chirps//20200613.tif" "data/chirps//20200614.tif"
 [15] "data/chirps//20200615.tif" "data/chirps//20200616.tif"
 [17] "data/chirps//20200617.tif" "data/chirps//20200618.tif"
 [19] "data/chirps//20200619.tif" "data/chirps//20200620.tif"
 [21] "data/chirps//20200621.tif" "data/chirps//20200622.tif"
 [23] "data/chirps//20200623.tif" "data/chirps//20200624.tif"
 [25] "data/chirps//20200625.tif" "data/chirps//20200626.tif"
 [27] "data/chirps//20200627.tif" "data/chirps//20200628.tif"
 [29] "data/chirps//20200629.tif" "data/chirps//20200630.tif"
 [31] "data/chirps//20200701.tif" "data/chirps//20200702.tif"
 [33] "data/chirps//20200703.tif" "data/chirps//20200704.tif"
 [35] "data/chirps//20200705.tif" "data/chirps//20200706.tif"
 [37] "data/chirps//20200707.tif" "data/chirps//20200708.tif"
 [39] "data/chirps//20200709.tif" "data/chirps//20200710.tif"
 [41] "data/chirps//20200711.tif" "data/chirps//20200712.tif"
 [43] "data/chirps//20200713.tif" "data/chirps//20200714.tif"
 [45] "data/chirps//20200715.tif" "data/chirps//20200716.tif"
 [47] "data/chirps//20200717.tif" "data/chirps//20200718.tif"
 [49] "data/chirps//20200719.tif" "data/chirps//20200720.tif"
 [51] "data/chirps//20200721.tif" "data/chirps//20200722.tif"
 [53] "data/chirps//20200723.tif" "data/chirps//20200724.tif"
 [55] "data/chirps//20200725.tif" "data/chirps//20200726.tif"
 [57] "data/chirps//20200727.tif" "data/chirps//20200728.tif"
 [59] "data/chirps//20200729.tif" "data/chirps//20200730.tif"
 [61] "data/chirps//20200731.tif" "data/chirps//20200801.tif"
 [63] "data/chirps//20200802.tif" "data/chirps//20200803.tif"
 [65] "data/chirps//20200804.tif" "data/chirps//20200805.tif"
 [67] "data/chirps//20200806.tif" "data/chirps//20200807.tif"
 [69] "data/chirps//20200808.tif" "data/chirps//20200809.tif"
 [71] "data/chirps//20200810.tif" "data/chirps//20200811.tif"
 [73] "data/chirps//20200812.tif" "data/chirps//20200813.tif"
 [75] "data/chirps//20200814.tif" "data/chirps//20200815.tif"
 [77] "data/chirps//20200816.tif" "data/chirps//20200817.tif"
 [79] "data/chirps//20200818.tif" "data/chirps//20200819.tif"
 [81] "data/chirps//20200820.tif" "data/chirps//20200821.tif"
 [83] "data/chirps//20200822.tif" "data/chirps//20200823.tif"
 [85] "data/chirps//20200824.tif" "data/chirps//20200825.tif"
 [87] "data/chirps//20200826.tif" "data/chirps//20200827.tif"
 [89] "data/chirps//20200828.tif" "data/chirps//20200829.tif"
 [91] "data/chirps//20200830.tif" "data/chirps//20200831.tif"
 [93] "data/chirps//20200901.tif" "data/chirps//20200902.tif"
 [95] "data/chirps//20200903.tif" "data/chirps//20200904.tif"
 [97] "data/chirps//20200905.tif" "data/chirps//20200906.tif"
 [99] "data/chirps//20200907.tif" "data/chirps//20200908.tif"
[101] "data/chirps//20200909.tif" "data/chirps//20200910.tif"
[103] "data/chirps//20200911.tif" "data/chirps//20200912.tif"
[105] "data/chirps//20200913.tif" "data/chirps//20200914.tif"
[107] "data/chirps//20200915.tif" "data/chirps//20200916.tif"
[109] "data/chirps//20200917.tif" "data/chirps//20200918.tif"
[111] "data/chirps//20200919.tif" "data/chirps//20200920.tif"
[113] "data/chirps//20200921.tif" "data/chirps//20200922.tif"
[115] "data/chirps//20200923.tif" "data/chirps//20200924.tif"
[117] "data/chirps//20200925.tif" "data/chirps//20200926.tif"
[119] "data/chirps//20200927.tif" "data/chirps//20200928.tif"
[121] "data/chirps//20200929.tif" "data/chirps//20200930.tif"

Raster Layers

We now create one multi-layered raster for each year, and store all years in one large list.

years <- years %>% map(~.x %>% rast)

For example, each of the 122 days from the 2020 rainy season are now layered together in a single raster.

years$`2020`

class       : SpatRaster 
dimensions  : 115, 159, 122  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
sources     : 20200601.tif  
              20200602.tif  
              20200603.tif  
              ... and 119 more source(s)
names       : 20200601, 20200602, 20200603, 20200604, 20200605, 20200606, ...

Seasonal Rainfall Accumulation

We could now use sum to add all of the daily rainfall totals from the 2020 rainy season. This reduces the number of layers from 122 to 1.

years$`2020` %>% sum()

class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 325.3491 
max value   : 1142.682

More efficiently, we’ll apply the same sum function to every year in our list. Let’s call this output chirps_seasonal_sum.

chirps_seasonal_sum <- map(years, ~.x %>% sum)

$`2001`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 228.5823 
max value   : 959.8677 

$`2002`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 196.6834 
max value   : 964.7353 

$`2003`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 214.7835 
max value   : 1257.437 

$`2004`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 199.3171 
max value   : 1003.068 

$`2005`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 252.3673 
max value   : 1007.607 

$`2006`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 187.3084 
max value   : 990.2568 

$`2007`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 219.7993 
max value   : 1083.782 

$`2008`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   :  194.591 
max value   : 1111.472 

$`2009`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 163.6973 
max value   : 1222.483 

$`2010`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 229.8995 
max value   : 1201.958 

$`2011`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 198.7203 
max value   : 953.9536 

$`2012`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 292.3781 
max value   : 1036.448 

$`2013`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 218.7261 
max value   : 902.7034 

$`2014`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 203.6023 
max value   :  1049.24 

$`2015`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 229.7149 
max value   : 1156.788 

$`2016`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 259.0644 
max value   : 1096.824 

$`2017`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 207.8768 
max value   : 1072.872 

$`2018`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 275.9608 
max value   : 1165.002 

$`2019`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 216.4114 
max value   : 1051.263 

$`2020`
class       : SpatRaster 
dimensions  : 115, 159, 1  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
name        :      sum 
min value   : 325.3491 
max value   : 1142.682

One Layer per Year

Now that each year in our list contains only one layer each, we can generate a new multi-layered raster: one layer per year.

chirps_seasonal_sum <- rast(chirps_seasonal_sum)

class       : SpatRaster 
dimensions  : 115, 159, 20  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
sources     : memory  
              memory  
              memory  
              ... and 17 more source(s)
names       :      2001,      2002,      2003,      2004,      2005,      2006, ... 
min values  :  228.5823,  196.6834,  214.7835,  199.3171,  252.3673,  187.3084, ... 
max values  :  959.8677,  964.7353, 1257.4365, 1003.0681, 1007.6073,  990.2568, ...

For every 0.05 degrees lat by 0.05 degree lon, we now have the total seasonal rainfall accumulation for every year 2001-2020.

How rainy was 2020?

To answer this question, we’ll compare total seasonal accumulation in 2020 to the 20-year average.

Here is the average seasonal rainfall accumulation for each pixel (across all years):

chirps_avg <- mean(chirps_seasonal_sum)

And here is the standard deviation from that average:

chirps_sd <- stdev(chirps_seasonal_sum)

Finally we can use both to compute a Z-score for each pixel in each year.

chirps_z <- (chirps_seasonal_sum - chirps_avg) / chirps_sd

class       : SpatRaster 
dimensions  : 115, 159, 20  (nrow, ncol, nlyr)
resolution  : 0.05, 0.05  (x, y)
extent      : -5.549997, 2.400003, 9.349999, 15.1  (xmin, xmax, ymin, ymax)
coord. ref. : lon/lat WGS 84 (EPSG:4326) 
source      : memory 
names       :      2001,      2002,      2003,      2004,      2005,      2006, ... 
min values  : -1.760746, -2.891911, -1.898153, -2.491247, -2.167904, -2.341027, ... 
max values  : 1.6021578, 1.8960675, 3.2768042, 0.9467555, 2.5081893, 1.5739420, ...

2020 Seasonal Rainfall Accumulation

Total accumulation relative to local 20-year average

ggplot() + 
  layer_spatial(mask(chirps_z$`2020`, vect(shape), touches = FALSE)) + 
  layer_spatial(shape, alpha = 0) +
  theme_minimal() + 
  scale_fill_gradient2(low = "#D72B22", high = "#4375B7", na.value = "transparent") + 
  labs(fill = "Z-score (2001-2020)")

Questions about CHIRPS raster data?

5 - Bringing it All Together

Spatially Weighted Averages

Remember our example EA? It overlaps 8 CHIRPS pixels.

test_buffer <- ea_summary_gps %>% 
  filter(ea == test_ea)

ggplot() + 
  layer_spatial(
    chirps_z$`2020` %>% 
      crop(test_buffer, snap = "out")
  ) + 
  layer_spatial(test_buffer, alpha = 0) + 
  theme_minimal() + 
  scale_fill_gradient2(
    high = "#4375B7", 
    limits = c(0, 2)
  )

Spatially Weighted Averages

We want a spatial average of these 8 pixels, where the “weight” is the proportion of the pixel included in the buffer zone.

test_z <- chirps_z$`2020` %>%
  extract(vect(test_buffer), weights = TRUE)

  ID     2020 weight
1  1 1.023793   0.01
2  1 1.110467   0.35
3  1 1.270147   0.24
4  1 1.160226   0.26
5  1 1.250536   1.00
6  1 1.327806   0.53
7  1 1.422373   0.18
8  1 1.379684   0.03

test_z %>% summarise(
  wtd_mean = weighted.mean(`2020`, weight)
)

  wtd_mean
1 1.252726

Enumeration Area Z-scores

Link by row ID

ea_summary_gps <- ea_summary_gps %>% rowid_to_column("ID")

Simple feature collection with 167 features and 6 fields
Geometry type: POLYGON
Dimension:     XY
Bounding box:  xmin: -5.32361 ymin: 10.24743 xmax: 0.7204144 ymax: 14.25915
Geodetic CRS:  WGS 84
# A tibble: 167 × 7
      ID        ea urban birth_prop ntile many_births                   geometry
   <int>     <dbl> <lgl>      <dbl> <int> <lgl>                    <POLYGON [°]>
 1     1 854111012 TRUE      0.253      2 TRUE        ((-3.856566 11.95614, -3.…
 2     2 854111006 TRUE      0.107      1 FALSE       ((-3.02159 11.87068, -3.0…
 3     3 854111002 TRUE      0.0469     1 FALSE       ((-3.202698 12.88706, -3.…
 4     4 854111007 FALSE     0.218      2 TRUE        ((-2.790317 12.89155, -2.…
 5     5 854111011 FALSE     0.150      2 TRUE        ((-3.474768 12.52022, -3.…
 6     6 854111008 FALSE     0.209      2 TRUE        ((-3.864223 13.27047, -3.…
 7     7 854191039 TRUE      0.196      2 TRUE        ((-3.235588 11.51495, -3.…
 8     8 854111003 TRUE      0.190      2 TRUE        ((-3.322203 12.54741, -3.…
 9     9 854191008 FALSE     0.190      2 TRUE        ((-4.30137 11.91649, -4.3…
10    10 854111010 TRUE      0.148      2 TRUE        ((-3.205145 12.61123, -3.…
# … with 157 more rows

Enumeration Area Z-scores

Calculate one z-score per row ID

ea_summary_z <- chirps_z$`2020` %>% 
  extract(vect(ea_summary_gps), weights = TRUE) %>% 
  tibble() %>% 
  group_by(ID) %>% 
  summarise(z = weighted.mean(`2020`, weight))

# A tibble: 167 × 2
      ID     z
   <dbl> <dbl>
 1     1 0.863
 2     2 0.601
 3     3 0.472
 4     4 0.790
 5     5 0.860
 6     6 1.37 
 7     7 0.911
 8     8 0.672
 9     9 0.704
10    10 0.498
# … with 157 more rows

Enumeration Area Z-scores

… and join z-scores back with the ea codes for each enumeration area

ea_summary_z <- ea_summary_gps %>% 
  st_drop_geometry() %>% 
  select(ID, ea) %>% 
  full_join(ea_summary_z, by = "ID")

# A tibble: 167 × 3
      ID        ea     z
   <dbl>     <dbl> <dbl>
 1     1 854111012 0.863
 2     2 854111006 0.601
 3     3 854111002 0.472
 4     4 854111007 0.790
 5     5 854111011 0.860
 6     6 854111008 1.37 
 7     7 854191039 0.911
 8     8 854111003 0.672
 9     9 854191008 0.704
10    10 854111010 0.498
# … with 157 more rows

Merging Z-scores with PMA data

We’ll use transmute to select a handful of variables from pma to use in our analysis.

pma_chirps <- pma %>% 
  transmute(
    ea = EAID_1, 
    wt = PANELWEIGHT,
    birth = PANELBIRTH_2 == 1,
    urban = URBAN == 1
  )

# A tibble: 5,487 × 4
          ea    wt birth urban
       <dbl> <dbl> <lgl> <lgl>
 1 854111005 2.50  TRUE  FALSE
 2 854111004 2.61  TRUE  FALSE
 3 854161007 3.21  FALSE FALSE
 4 854141008 0.538 FALSE TRUE 
 5 854191022 0.358 FALSE FALSE
 6 854141002 3.20  FALSE FALSE
 7 854131034 0.404 FALSE TRUE 
 8 854191036 0.314 TRUE  FALSE
 9 854121003 0.337 FALSE TRUE 
10 854231003 2.55  FALSE FALSE
# … with 5,477 more rows

Merging Z-scores with PMA data

We’ll use transmute to select a handful of variables from pma to use in our analysis.

pma_chirps <- pma %>% 
  transmute(
    ea = EAID_1, 
    wt = PANELWEIGHT,
    birth = PANELBIRTH_2 == 1,
    urban = URBAN == 1
  )

Another full_join allows us to merge ea_summary_z for each woman’s enumeration area.

pma_chirps <- pma_chirps %>% full_join(ea_summary_z, by = "ea")

# A tibble: 5,487 × 6
          ea    wt birth urban    ID     z
       <dbl> <dbl> <lgl> <lgl> <dbl> <dbl>
 1 854111005 2.50  TRUE  FALSE    12 1.18 
 2 854111004 2.61  TRUE  FALSE    13 1.21 
 3 854161007 3.21  FALSE FALSE    75 0.375
 4 854141008 0.538 FALSE TRUE     53 1.25 
 5 854191022 0.358 FALSE FALSE   107 0.767
 6 854141002 3.20  FALSE FALSE    51 1.13 
 7 854131034 0.404 FALSE TRUE     28 1.22 
 8 854191036 0.314 TRUE  FALSE    96 0.593
 9 854121003 0.337 FALSE TRUE     17 1.18 
10 854231003 2.55  FALSE FALSE   166 0.418
# … with 5,477 more rows

Z-scores in hierarchical models

The lme4 package allows us to build a hierarchical model with EA random effects.

For example, a simple model interacting rainfall with urban:

glmer(
  birth ~ z*urban + (1 | ea), 
  data = pma_chirps,
  family = "binomial") %>%
  tidy(exp = TRUE, conf.int = TRUE) %>%
  mutate(sig = gtools::stars.pval(p.value))

# A tibble: 5 × 10
  effect   group term            estimate std.error statistic   p.value conf.low conf.high sig  
  <chr>    <chr> <chr>              <dbl>     <dbl>     <dbl>     <dbl>    <dbl>     <dbl> <chr>
1 fixed    <NA>  (Intercept)        0.153    0.0231   -12.4    1.46e-35    0.114     0.205 "***"
2 fixed    <NA>  z                  1.27     0.161      1.91   5.63e- 2    0.994     1.63  "."  
3 fixed    <NA>  urbanTRUE          1.09     0.240      0.376  7.07e- 1    0.705     1.68  " "  
4 fixed    <NA>  z:urbanTRUE        0.635    0.124     -2.32   2.01e- 2    0.433     0.931 "*"  
5 ran_pars ea    sd__(Intercept)    0.265   NA         NA     NA          NA        NA     ""

No controls, but we do so see some evidence that a wetter rainy season might increase odds for a birth that year.

Survey weights

lme4 does not provide a nice way to incorporate survey weights (inverse selection probability).

Instead, you might consider the survey package for weights and in a logit model with cluster-robust SEs.

pma_chirps %>%
  as_survey_design(weight = wt, id = ea) %>%
  svyglm(birth ~ z*urban, design = ., family = "quasibinomial") %>%
  tidy(exp = TRUE, conf.int = TRUE) %>%
  mutate(sig = gtools::stars.pval(p.value))

# A tibble: 4 × 8
  term        estimate std.error statistic  p.value conf.low conf.high sig  
  <chr>          <dbl>     <dbl>     <dbl>    <dbl>    <dbl>     <dbl> <chr>
1 (Intercept)    0.172    0.167    -10.6   3.29e-20    0.124     0.239 "***"
2 z              1.21     0.0894     2.12  3.55e- 2    1.01      1.44  "*"  
3 urbanTRUE      0.868    0.229     -0.616 5.39e- 1    0.552     1.37  " "  
4 z:urbanTRUE    0.736    0.180     -1.70  9.06e- 2    0.515     1.05  "."

Similar results: some evidence that a wetter rainy season might increase odds for a birth that year.

Some other things to consider

When does rainfall occur relative to conception?
What is the relevant comparison period? (CHRIPS data are available from 1981)
Does the rainy season vary across the study area?
How does rainfall interact with temperature, vegetation, and local livelihoods?

Technical issues:

Should I store climate data locally, or access through a server? (Check out the CHIRPS API package for R!)
How much memory does R need to process my analysis? Can I break it up into pieces, or use parallel processing?

Resources

r-spatial - blog from the authors of sf
rspatial - blog from the authors of terra
PMA Data Analysis Hub - our blog!
IPUMS.org (and IPUMS Global Health in particular)
Find us on Twitter: @ipumsGH

Thank you!