[R] Problem with the grep function
Wolski
wolski at molgen.mpg.de
Thu Jul 8 09:36:40 CEST 2004
Hi!
For exact matches you can use
== or is.element.
To get the indices use which.
e.g. ==
> x<-c("a","b","ab")
> x=="a"
[1] TRUE FALSE FALSE
> which((x=="a")==T)
[1] 1
or
e.g. is.element
> is.element(x,"a")
[1] TRUE FALSE FALSE
> which(is.element(x,"a")==TRUE)
[1] 1
>
Sincerely
Eryk
*********** REPLY SEPARATOR ***********
On 7/8/2004 at 9:20 AM aubert at inapg.fr wrote:
>>>Let me present to you my problem :
>>>
>>>I have a character vector x and I would like to obtain the indices of
>>>the
>>>elements of
>>>this vector that yielded exactly a match.
>>>
>>>For example, x=nom, pattern="b", I would to obtain 2 because "b" is on
>>>the
>>>second position.
>>>
>>>First program :
>>>nom <- c("a","b","ab")
>>>grep("b",nom)
>>>2 3
>>>
>>>Then I try the option extended =FALSE (instead of TRUE by default) and I
>>>obtain '2 3' a second time.
>>>
>>>Please can you help me : How can I obtain only 2 in using the grep
>>>function
>>>(without using the match function).
>>>
>>>Thanks you
>>>
>>>Julie AUBERT
>>>
>>>______________________________________________
>>>R-help at stat.math.ethz.ch mailing list
>>>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
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Dipl. bio-chem. Eryk Witold Wolski @ MPI-Moleculare Genetic
Ihnestrasse 63-73 14195 Berlin 'v'
tel: 0049-30-83875219 / \
mail: wolski at molgen.mpg.de ---W-W---- http://www.molgen.mpg.de/~wolski
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