[R] How to import specific column(s) using "read.table"?
f.duan at yale.edu
Tue Aug 10 21:55:45 CEST 2004
Thanks a lot.
Your way works perfect. And one more tiny question related to your codes:
My data file has many columns to be omitted (suppose the first 20 ones), but I
found "scan(myfile, what=list(rep(NULL, 20), rep(0, 5))" doesn't work. I had to
to type "NULL" 20 times and "0" five times in the "list(...)".
But anyway, it works and saves a lot of memory for me. Thank you again.
Quoting Gabor Grothendieck <ggrothendieck at myway.com>:
> Gabor Grothendieck <ggrothendieck <at> myway.com> writes:
> : F Duan <f.duan <at> yale.edu> writes:
> : > I have a very big tab-delim txt file with header and I only want to
> : > several columns into R. I checked the options for Â"read.tableÂ" and only
> : Try using scan with the what=list(...) and flush=TRUE arguments.
> : For example, if your data looks like this:
> : 1 2 3 4
> : 5 6 7 8
> : 9 10 11 12
> : 13 14 15 16
> : then you could read columns 2 and 4 into a list with:
> oops. That should be 1 and 3.
> : scan(myfile, what = list(0, NULL, 0), flush = TRUE)
> : or read in and convert to a data frame via:
> : do.call("cbind", scan(myfile, what = list(0, NULL, 0), flush = TRUE))
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