On Apr 23, 2012, at 12:25 PM, Paul Miller wrote:
Hello Dr. Winsemius,
Unfortunately, I also have terms like "krasmutated". So simply
selecting words that start with "muta" won't work in this case.
You are aware that negative indexing can be used with grep aren't you?
--
David.
Thanks,
Paul
--- On Mon, 4/23/12, David Winsemius <dwinsem...@comcast.net> wrote:
From: David Winsemius <dwinsem...@comcast.net>
Subject: Re: [R] Selecting columns whose names contain "mutated"
except when they also contain "non" or "un"
To: "Paul Miller" <pjmiller...@yahoo.com>
Cc: r-help@r-project.org
Received: Monday, April 23, 2012, 11:16 AM
On Apr 23, 2012, at 12:10 PM, Paul Miller wrote:
Hello All,
Started out awhile ago trying to select columns in a
dataframe whose names contain some variation of the word
"mutant" using code like:
names(KRASyn)[grep("muta", names(KRASyn))]
The idea then would be to add together the various
columns using code like:
KRASyn$Mutant_comb <- rowSums(KRASyn[grep("muta",
names(KRASyn))])
What I discovered though, is that this selects columns
like "nonmutated" and "unmutated" as well as columns like
"mutated", "mutation", and "mutational".
So I'd like to know how to select columns that have
some variation of the word "mutant" without the "non" or the
"un". I've been looking around for an example of how to do
that but haven't found anything yet.
Can anyone show me how to select the columns I need?
If you want only columns whose names _begin_ with "muta"
then add the "^" character at the beginning of your
pattern:
names(KRASyn)[grep("^muta", names(KRASyn))]
(This should be explained on the ?regex page.)
--
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
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