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

[David Winsemius]

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 <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
>>
>>

David Winsemius, MD
West Hartford, CT