Re: [R] Read every second line from ASCII file

From: Roland Rau <roland.rproject_at_gmail.com>
Date: Wed, 02 May 2007 11:50:27 -0400

Dear all,

I just realized that I forgotten to write some kind of final email for this thread and to thank you for your help. It seems that the recommeneded procedure in such circumstances has three steps:

1) readLines()
2) select the desired lines
3) strsplit()

Thanks Ferdinand, Jim, and Paul!
Roland

Roland Rau wrote:
> Dear all,
>
> I have an ASCII file where records are separated by a blank. I would
> like to read those data; however, only the data in rows 1, 3, 5, 7, ...
> are important; the other lines (2,4,6,8,....) contain no useful
> information for me.
> So far I used awk/gawk to do it:
> gawk '{if ((FNR % 2) != 0) {print $0}}' infile.txt > outfile.txt
>
> What is the recommended way to accomplish this in R?
> Simply reading the whole file, and deleting all the even-numbered lines
> is not straightforward since these lines have different length (whereas
> lines 1,3,5,7,... have the same length).
>
> I 'RSiteSearched' for "read every second line from a file" but this
> search did not yield the desired result.
> Also trying out the arguments nrows and skip from read.table() did not
> help.
>
> Maybe someone knows an easy way to do it from within R? -- of course not
> using system("gawk ....") :-)
> If not, it does not matter too much since I get the job done easily with
> awk.
>
> Thanks,
> Roland
>
>
>
>



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