[R] Read every second line from ASCII file

Roland Rau roland.rproject at gmail.com
Wed May 2 17:50:27 CEST 2007

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

Thanks Ferdinand, Jim, and Paul!

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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