[R] Faster Printing Alternatives to 'cat'

[Henrik Bengtsson]

Do it in chunks of rows. /H

On Sat, Jan 17, 2009 at 6:55 AM, Gundala Viswanath <gundalav at gmail.com> wrote:
> Hi Hadley,
>
> I had to do it by line. Because, in practice, I will
> manipulate the figures and string before printing it.
>
> And I can't bind these results into one new object,
> because there are literally millions of this lines, and
> R object can't handle that in my 4GB Ram memory.
>
> I tried your suggestion already, I have memory problem
>
>> x <- cbind(dat$V1, as.character(dat$V2))
> Error: cannot allocate vector of size 4.2 Gb
> Execution halted
>
> - Gundala Viswanath
> Jakarta - Indonesia
>
>
>
> On Sat, Jan 17, 2009 at 11:39 PM, hadley wickham <h.wickham at gmail.com> wrote:
>> 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/
>>
>
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