grep for multiple pattern?

use the "|" in regular expressions:

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

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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