CODEWITHSUNDEEP
rnetcdfr-raster
gren
gren

Reputation: 21

open multiple .nc then write multiple raster

I am a new programmer. Recently I was given 1,850 .nc files which I subsetted to 480 files. Each filename has a number to indicate the month. All I want to do is:

  1. open all .nc files
  2. write all .nc files to raster format
  3. average all raster files in 12 files, one for each month.

I know this shouldn't be difficult but I am having trouble. So far I haven't gotten past step 2:

library(RNetCDF)
library(raster)
library(rgdal)

files=list.files(pattern='*.nc', full.names=TRUE)

for (i in seq_along(files)){
 nc=open.nc(files[i])}

list(nc) 

for(i in 1:length(nc)){
  rnc<-raster(nc[i])
  writeRaster(rnc, filename=names(rnc), bylayer=TRUE, format="GTiff")}

As you all can tell, I am still a newbie/student of R, I think I have step 1 OK, the for loop for step 2 does not seem to be working. Once I get 1 and 2 completed, I can work on 3 (if you all can see an easy answer for step 3 please share).

Thank you.

Upvotes: 1

Views: 1098

Answers (1)

Robert Hijmans
Robert Hijmans

Reputation: 47146

You can do something like this:

library(raster)
library(ncdf4)
files <- list.files(pattern='*.nc', full.names=TRUE)

Either:

s <- stack(files)
rnc <- writeRaster(s, filename="x", bylayer=TRUE, format="GTiff")}

Or with a loop:

for (f in files) {
    r <- raster(f)
    fout <- extension(f, '.tif')
    r <- writeRaster(r, filename=fout, datatype='FLT4S')
}

To get monthly averages, you can do something like:

months <- stackApply(s, 1:12, mean)

Assuming that the files are in the right order.

Upvotes: 3

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