grep for multiple pattern?

Hi

Maybe I am missing something but isn't  this

which(letters %in% c("a", "x"))

what you want?

Petr

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Rainer M Krug
Sent: Thursday, February 13, 2014 3:43 PM
To: R-help at r-project.org
Subject: [R] grep for multiple pattern?

Hi

I want to search for multiple pattern as grep is doing for a single
pattern, but this obviously not work:

grep("an", month.name)

[1] 1

grep("em", month.name)

[1]  9 11 12

grep("eb", month.name)

[1] 2

grep(c("an", "em", "eb"), month.name)

[1] 1
Warning message:
In grep(c("an", "em", "eb"), month.name) :
  argument 'pattern' has length > 1 and only the first element will be
used

Is there an equivalent which returns the positions as grep is doing,
but not using the strict full-string matching of match()?

I could obviously do:

unlist( sapply(pat, grep, month.name ) )

 an em1 em2 em3  eb
  1   9  11  12   2

but is there a more compact command I am missing?

Thanks,

Rainer

--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology Stellenbosch University South
Africa

Tel :       +33 - (0)9 53 10 27 44
Cell:       +33 - (0)6 85 62 59 98
Fax :       +33 - (0)9 58 10 27 44

Fax (D):    +49 - (0)3 21 21 25 22 44

email:      Rainer at krugs.de

Skype:      RMkrug

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