[R-sig-Geo] temp files in raster

[Diann Prosser]

Hi R geo gurus-

I am using the raster package to run functions on large spatial datasets
(>19million cells * many iterations thereby producing large arrays or
brickrasters). 

The system has written my function to a temporary file because it is too
large to be held in memory. *Can only 1 temporary file be used? If I try to
run a subsequent function, I get an error (see below) that my temporary grid
already exists and that I should allow OVERWRITE (which I don't want). 

Is it a problem to use temporary files in this manner* *(i.e., should I
already be manually saving them to disk)?*

Thanks for any advice you might have.

the error:
> system.time(stBSte1 <- calc(s3, FUNstBSte1))
Error in .startRasterWriting(x, filename, format = filetype, ...) : 
  C:/Users/Diann/AppData/Local/Temp/R_raster_tmp/raster_tmp_9271340493.grd
exists. use 'overwrite=TRUE' if you want to overwrite it
Timing stopped at: 0.19 0 0.18 

some other info:
> showTmpFiles()
raster_tmp_5942113574 raster_tmp_67775104885 raster_tmp_9271340493 
> rasterTmpFile()
[1]
"C:/Users/Diann/AppData/Local/Temp/R_raster_tmp/raster_tmp_5652878174.grd"


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