[R] Using gregexpr with multiple search elements

[Christos Hatzis]

gregexpr("\\at|\\og", text) 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Corey Sparks
> Sent: Wednesday, February 25, 2009 11:50 AM
> To: R Help
> Subject: [R] Using gregexpr with multiple search elements
> 
> Dear list,
> I am trying to use gregexpr to see if entries in a dataframe 
> have either of two possible values for a string.
> here's an example
> text<-c("fat", "rat", "cat", "dog", "log", "fish")
> 
> If I just wanted to find if any one of the elements in text 
> match the pattern "at" I would do gregexpr("\\at", text)
> 
> which would match on the first three elements, you can do 
> something like ifelse(gregexpr("\\at",text)>-1, 1,0)
> 
> to see if a particular entry in the data "text" is matched.
> My problem is I need to check if either of two patterns match 
> in the data, an example that doesn't work is 
> gregexpr(c("\\at", "\\og"), text)
> 
> which is the basic form of what I'm looking to do, if this 
> would work I would get a match for elements 1 through 5 of 
> text, since either "at" or "og" occurs.
> 
> If anyone might have an idea about this I would greatly appreciate it.
> Best,
> Corey
> 
> Corey Sparks
> Assistant Professor
> Department of Demography and Organization Studies University 
> of Texas at San Antonio One UTSA Circle San Antonio, TX 78249 
> 210 458 6858 corey.sparks at utsa.edu
> 
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