I have a large raster stack composed of dozens of layers. I would like to save each layer directly to disk with ifel however the filename function within ifel creates a single output file. The help file for ifel directs towards writeRaster for additional arguments but in writeRaster, each layer is saved individually which is what I would like.
r <- rast(nrows=5, ncols=5, xmin=0, xmax=1, ymin=0, ymax=1)
values(r) <- c(-10:0, NA, NA, NA, 0:10)
s<-r*1.2
r.stack<-c(r, s)
names(r.stack)<-c("r", "s")
t <- rast(nrows=5, ncols=5, xmin=0, xmax=1, ymin=0, ymax=1)
values(t) <- c(rep(1, 5), rep(2, 5), rep(3, 5), rep(2, 5), rep(3, 5))
x <- ifel(t==3, 5, r.stack,
filename=paste("test",names(r.stack), ".tiff", sep=""))
#Warning message:
#[cover] only the first filename supplied is used
output: a single .tiff file with both layers
desired output: two .tiff files for each layer named with the layer name
writeRaster(x,filename=paste("test",names(r.stack), ".tiff", sep=""))
filename works differently inside ifel() as it can only write a single output file. In this instance, it is designed to save the modifications made to a single input object.
On the other hand, writeRaster() accepts:
a single filename, or as many filenames as nlyr(x) to write a file for each layer.
To achieve your desired outcome:
library(terra)
# Create modified version of t SpatRaster
x <- ifel(t == 3, 5, r.stack)
# Write each layer in x to woring directory
writeRaster(x,
filename = paste("test", names(r.stack), ".tiff", sep = ""),
overwrite = TRUE)
# List all tiff files starting with "test" in working directory
list.files(pattern = "^test.*\\.tiff$")
# [1] "testr.tiff" "tests.tiff"
rast("testr.tiff")
# class : SpatRaster
# dimensions : 5, 5, 1 (nrow, ncol, nlyr)
# resolution : 0.2, 0.2 (x, y)
# extent : 0, 1, 0, 1 (xmin, xmax, ymin, ymax)
# coord. ref. : lon/lat WGS 84 (EPSG:4326)
# source : testr.tiff
# name : r
# min value : -10
# max value : 5
rast("tests.tiff")
# class : SpatRaster
# dimensions : 5, 5, 1 (nrow, ncol, nlyr)
# resolution : 0.2, 0.2 (x, y)
# extent : 0, 1, 0, 1 (xmin, xmax, ymin, ymax)
# coord. ref. : lon/lat WGS 84 (EPSG:4326)
# source : tests.tiff
# name : s
# min value : -12
# max value : 6