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(...)".
That's because rep(NULL, 20) returns a single NULL -- it's not obvious what else it could sensibly return. What you need to do is replicate 20 times a list containing NULL (and a list containing NULL is quite a different object to NULL). E.g.:
> rep(NULL, 20) NULL > c(rep(list(NULL), 3), rep(list(0), 2)) [[1]]: NULL
[[2]]: NULL
[[3]]: NULL
[[4]]: [1] 0
[[5]]: [1] 0
>
Tony Plate
But anyway, it works and saves a lot of memory for me. Thank you again.
Frank
Quoting Gabor Grothendieck <[EMAIL PROTECTED]>:
> 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
> import
> : > several columns into R. I checked the options for read.table 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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