On Mon, Feb 2, 2009 at 6:40 PM, Laura Rodriguez Murillo <
laura.lmurillo@gmail.com> wrote:

> Hi dear list,
>
> I'm trying to use a package to perform some analysis but I need to
> process a file first of all. I have file A with 6 columns and 443816
> rows and I need to select from here the rows where the string in the
> first column is present in file B that has 333751 rows and only one
> column. So all the strings in file B are present in the first column
> of file A but the contrary is not true. I'm kind of stuck with this
> matter so I would appreciate any help.
>

One of the simplest R ways to handle this is to read both files into R using
read.table and then use the merge() function to get "merge" the two data
sets.  Merge allows one to specify what rows to keep based on presence in
the two objects being merged.

Sean

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