[R] substring comparison

[David Winsemius]

On Apr 29, 2010, at 1:17 PM, Claus O'Rourke wrote:

> Hi all,
>
> I'm writing a script to do some basic text analysis in R. Let's assume
> I have a data frame named data which contains a column named 'utt'
> which contains strings. Is there a straightforward way to achieve
> something like this:
>
> data$ContainsThe <- ifelse(startsWith(data$Utt,"the"),"y","n")
>
> or
>
> data$ContainsThe <- ifelse(contains(data$Utt,"the"),"y","n")
> ?
>
> I tried using grep
> data$ContainsThe <- ifelse(grep("the",data$Utt),"y","n")
>
> but this doesn't work

> becausee grep only returns the rows for which
> grep succeeded.

?grepl    # which is on the same help page as grep


>
> Thanks for any pointers
>
> Claus

David Winsemius, MD
West Hartford, CT