CODEWITHSUNDEEP
rr-raster
loening
loening

Reputation: 13

Count freq of multiple raster objects in R

I want to write a df with the freq of 150 raster objects.

I know I can read individual raster objects with 

raster_x <- raster::raster()

I can further get the freq with 

raster_freq_y <- raster::freq(raster_x)

After that I can bind the freq outputs of multiple raster objects to a df with 

cbind.data.frame(raster_freq_x, raster_freq_y)

What I dont know is how to do this for 150 raster objects in one go?

Should I use a loop? If so what kind of loop would make sense?

Any help is appreciated.

Upvotes: 1

Views: 256

Answers (1)

Robert Hijmans
Robert Hijmans

Reputation: 47146

If the RasterLayer objects have the same extent and resolution, you can combine them in a RasterStack. The below example is from ?freq

Example data:

library(raster)
r <- raster(nrow=18, ncol=36)
r[] <- runif(ncell(r))
r[1:5] <- NA
s <- stack(r, r*2, r*3)

Solution:

freq(s, merge=TRUE)

If the RasterLayer objects do not have the same extent and resolution, you can keep them together in a list and use lapply

ss <- list(r, r*2, r*3)
lapply(ss, freq)

Upvotes: 1

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