grep for multiple pattern?

On 02/13/14, 17:23 , jim holtman wrote:

use the "|" in regular expressions:

  grep(c("an|em|eb", month.name <http://month.name/>)

Thanks - again a reason to learn regexp.

Cheers,

Rainer

Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.


On Thu, Feb 13, 2014 at 9:43 AM, Rainer M Krug <Rainer at krugs.de
<mailto:Rainer at krugs.de>> wrote:

     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 <http://month.name>)

     [1] 1

     > grep("em", month.name <http://month.name>)

     [1]  9 11 12

     > grep("eb", month.name <http://month.name>)

     [1] 2

     > grep(c("an", "em", "eb"), month.name <http://month.name>)

     [1] 1
     Warning message:
     In grep(c("an", "em", "eb"), month.name <http://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 <http://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

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