[R] which LETTERS?

[Ivan Calandra]

Hi Charles,

I think you're looking for %in%:
which(LETTERS %in% c("A", "B", "C"))

See ?"%in%" for details

Basically, with "==", the vector c("A","B") or c("A","B","C") will be 
recycled and compared with LETTERS, which is not what you want. You want 
to match() LETTERS with the vector.

Maybe someone who better knows the correct terms will be able to explain 
better how it works.

HTH,
Ivan

--
Ivan Calandra, ATER
University of Reims Champagne-Ardenne
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ivan.calandra at univ-reims.fr
https://www.researchgate.net/profile/Ivan_Calandra

Le 10/11/14 13:50, Charles Stangor a écrit :
> I'm confused:
>
> Thanks in advance.
>
>> which(LETTERS == c("A"))
> [1] 1
>> which(LETTERS == c("A","B"))
> [1] 1 2
>> which(LETTERS == c("A","B","C"))
> [1] 1 2 3
> Warning message:
> In LETTERS == c("A", "B", "C") :
>    longer object length is not a multiple of shorter object length
>
>
> Charles Stangor
> Professor
> Dept of Psychology
> University of Maryland
> Academic Achievement Research Group <http://www.charlesstangor.com/AARG>
>
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>
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