R help - Oct 2008 - extract bits of a character vector

Dear list:



I have the following problem: From a vector like this:

vec<- c("mud_1999_area_A", "gravel_2004_area_F")



I would like to get the year in a separate vector, such



y<- c("1999", "2004")



I´ve been looking to grep() but I'm not sure how to do this.
Help?
Thanks in advance
J

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On 22/10/2008 5:02 PM, jonas garcia wrote:
> Dear list:
> 
> 
> 
> I have the following problem: From a vector like this:
> 
> vec<- c("mud_1999_area_A", "gravel_2004_area_F")
> 
> 
> 
> I would like to get the year in a separate vector, such
> 
> 
> 
> y<- c("1999", "2004")
> 
> 
> 
> I?ve been looking to grep() but I'm not sure how to do this.
You want sub() or gsub().  For example, if the year is always the only 
digits in the string, then

gsub("[^[:digit:]]", "", vec)

(which says delete all non-digits).

Duncan Murdoch