R help - Feb 2009 - 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

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
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 
>