[R] Faster Printing Alternatives to 'cat'

[hadley wickham]

On Sat, Jan 17, 2009 at 7:59 AM, gundalav <gundalav at gmail.com> wrote:
> Dear Jim and all,
>
> Allow me to ask your expert opinion.
>
>
> Using the data (16Mb) downloadable from here:
>
> http://drop.io/gundalav/asset/test-data-zip
>
>
> It took this long under 1994.070Mhz Cpu Linux, using
> "write.table"
>
>> proc.time() - ptm1
>     user    system   elapsed
> 16581.833  5787.228 21386.064
>
>
>
> __MYCODE__
>
> args <- commandArgs(trailingOnly=FALSE)
> fname <- args[3]
> dat <- read.delim(fname, header=FALSE);
>
> output <- file('output_writetable.txt', 'w')
>
>
> ptm1 <- proc.time()
> for (i in 1:nrow(dat)) {
>
>     #cat(dat$V1[i]," ", as.character(dat$V2[i]),"\n", sep="")
>     write.table(cbind(dat$V1[i], as.character(dat$V2[i])),
> file=output, sep="\t", quote=FALSE, col.names=FALSE, row.names=FALSE)
> }
>
> close(output)
> proc.time() - ptm1
> __END__
>
> Perhaps I misunderstood you. But seems that this is
> truly slow. Is there a way I can speed it up?

Don't do it line by line!

write.table(dat[, c("V1", "V2")], file='output_writetable.txt',
sep="\t", quote=FALSE, col.names=FALSE, row.names=FALSE)

Hadley

-- 
http://had.co.nz/