[R] Selecting columns whose names contain "mutated" except when they also contain "non" or "un"

[Paul Miller]

Hello Dr. Winsemius,

Unfortunately, I also have terms like "krasmutated". So simply selecting words that start with "muta" won't work in this case. 

Thanks,

Paul


--- On Mon, 4/23/12, David Winsemius <dwinsemius at comcast.net> wrote:

> From: David Winsemius <dwinsemius at comcast.net>
> Subject: Re: [R] Selecting columns whose names contain "mutated" except when they also contain "non" or "un"
> To: "Paul Miller" <pjmiller_57 at yahoo.com>
> Cc: r-help at 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
> 
>