[R] R "write" strange behavior in huge file
Stefan Evert (Mailing Lists)
stefanML at collocations.de
Wed Sep 17 15:39:16 CEST 2014
You probably told R to write out the file as a single long line with fields separated alternately by 380 TABs and one newline thats what the ncol argument does (write is just a small wrapper around cat()).
cat() doesnt print lines that are longer than 2 GiB, so it will insert an extra \n after every 2 GiB of data. (IIRC, this is because in the C code, fill=FALSE is replaced by fill=MAX_INT or so.)
The only way around this limitation that I can think of is to write a wrapper function that breaks up the matrix or list of vectors in smaller chunks and appends them separately to the output file. Im planning to add such a function to one of my packages, so Id be interested if somebody has a better solution.
On 16 Sep 2014, at 18:54, Maxime Vallee <ValleeM at iarc.fr> wrote:
> In my script I have one list of 1,132,533 vectors (each vector contains
> 381 elements).
> When I use "write" to save this list in a flat text file (I unlist my
> list, separate by tabs, and set ncol to 381), I end up with a file of
> 1,132,535 lines (2 additional lines). I checked back, my R list do not
> have those two additional items before writing.
> With awk, I determined if lines where not made of 381 fields: there were
> two, separated by around 400k lines.
> I made sub-files, using those "incomplete" lines as boundaries. My files
> are very close in size : 1.9 GB (respectively 1971841853 B and 1972614897
> B). It feels like a 32 bit / 64 bit issue.
> My R version is this:
> ./Rscript -e 'sessionInfo()$platform'
>  "x86_64-unknown-linux-gnu (64-bit)"
> There is somewhere, reaching 1.9 GB, something that is changing my tabs to
> unwanted carriage returns...
> Any idea that might cause this, and if it looks solvable in R?
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