[R] Read every second line from ASCII file

[jim holtman]

Use readLines and then just use the odd numbered lines:

x.in <- readLines(yourFile)
x.in <- x.in[seq(1, length(x.in), 2)] # every 2nd line

or just to make sure, only delete blank lines:

x.in <- x.in[!(x.in == "")]

On 4/30/07, Roland Rau <roland.rproject at gmail.com> 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
>
>        [[alternative HTML version deleted]]
>
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>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?