[R] extracting variables with patttern templates
ripley at stats.ox.ac.uk
Tue Oct 22 22:43:05 CEST 2002
What is X? The only things I can think of in R that could be thought to
contain datasets are lists, and they are extracted via [[ ]].
Or perhaps X is a data frame and you meant columns (`variables' but
perhaps also more general objects).
In either case you can do this by indexing. To extract all the columns of
a data frame whose name contains `a' I can use
and that allows regular expressions just like the `pattern' argument of
It's hard to give precise answers to vague questions, but I hope that
you enough of an idea.
On Tue, 22 Oct 2002, Rishabh Gupta wrote:
> Hi all,
> I was wondering, does R have a facility to extract datasets based on a string template. I know that you can do something like:
> X["a"] # extract from 'X' the dataset named 'a'.
> What I would like is something which says, from 'X' extract all the datasets that have an 'a':
> X[pat = "a"]
> I know that the 'pat' option can be used when just listing all the object that exist, but is there any way to extract only certain
> dataset from within an object using a smiliar technique.
> Any help would be greatly appreciated.
> Many Thanks!
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Brian D. Ripley, ripley at stats.ox.ac.uk
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