get_chirps {chirps}

R Documentation

Get CHIRPS precipitation data

Description

Get daily precipitation data from the "Climate Hazards Group". Two server sources are available. The first, "CHC" (default) is recommended for multiple data-points, while "ClimateSERV" is recommended when few data-points are required (~ 50).

Usage

get_chirps(object, dates, server, ...)

## Default S3 method:
get_chirps(object, dates, server, as.matrix = FALSE, ...)

## S3 method for class 'SpatVector'
get_chirps(object, dates, server = "CHC", as.raster = TRUE, ...)

## S3 method for class 'SpatRaster'
get_chirps(
  object,
  dates,
  server = "CHC",
  as.matrix = TRUE,
  as.raster = FALSE,
  ...
)

## S3 method for class 'sf'
get_chirps(object, dates, server, as.sf = FALSE, ...)

## S3 method for class 'geojson'
get_chirps(object, dates, server, as.geojson = FALSE, ...)

Arguments

object	input, an object of class data.frame (or any other object that can be coerced to data.frame), SpatVector, SpatRaster, sf or geojson
dates	a character of start and end dates in that order in the format "YYYY-MM-DD"
server	a character that represent the server source "CHC" or "ClimateSERV"
...	additional arguments passed to terra or sf methods See details
as.matrix	logical, returns an object of class matrix
as.raster	logical, returns an object of class SpatRaster
as.sf	logical, returns an object of class sf
as.geojson	logical, returns an object of class geojson

Details

Data description at https://data.chc.ucsb.edu/products/CHIRPS-2.0/README-CHIRPS.txt

Additional arguments when using server = "CHC"

resolution: numeric, resolution of CHIRPS tiles either 0.05 (default) or 0.25 degrees

Additional arguments when using server = "ClimateSERV"

dist: numeric, buffer distance for each object coordinate

nQuadSegs: integer, number of segments per buffer quadrant

operation: supported operations for ClimateSERV are:

operation		value
max	=	0
min	=	1
median	=	2
sum	=	4
average	=	5 (default value)

Value

A matrix, raster or a data frame of CHIRPS data:

id

the index for the rows in object

dates

the dates from which CHIRPS was requested

lon

the longitude as provided in object

lat

the latitude as provided in object

chirps

the CHIRPS value in mm

Note

get_chirps may return some warning messages given by sf, please look sf documentation for possible issues.

References

Funk C. et al. (2015). Scientific Data, 2, 150066.
doi: 10.1038/sdata.2015.66

Examples

library("chirps")
library("terra")

# Case 1: return as a data.frame
dates <- c("2017-12-15","2017-12-31")
lonlat <- data.frame(lon = c(-55.0281,-54.9857), lat = c(-2.8094, -2.8756))

r1 <- get_chirps(lonlat, dates, server = "CHC")

# Case 2: return a matrix
r2 <- get_chirps(lonlat, dates, server = "CHC", as.matrix = TRUE)

# Case 3: input SpatVector and return raster
f <- system.file("ex/lux.shp", package = "terra")
v <- vect(f)
r3 <- get_chirps(v, dates, server = "CHC", as.raster = TRUE)

# Case 4: using the server "ClimateSERV"
r4 <- get_chirps(lonlat, dates, server = "ClimateSERV")

# Case 5: from "ClimateSERV" and return as a matrix
r5 <- get_chirps(lonlat, dates, server = "ClimateSERV", as.matrix = TRUE)

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