[R] Read every second line from ASCII file

[Gabor Grothendieck]

I typically wouldn't use strsplit but would reread it using read.table
and textConnection as in:

http://www.mail-archive.com/r-help@stat.math.ethz.ch/msg84752.html


On 5/2/07, Roland Rau <roland.rproject at gmail.com> wrote:
> 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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