On May 3, 2016, at 11:16 PM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
Yes, but the answer is likely to depend on the actual patterns of
strings in your real data, so the sooner you go find a book or tutorial on
regular expressions the better. This is decidedly not R specific and there
are already lots of resources out there.
Given the example you provide, the pattern "age$" should work. However,
that is probably not sufficiently selective for a practical data set so
start learning to fish (design regex patterns) yourself.
@ Steven;
As is almost always the case I agree with Jeff. I found that reading Rhelp
and attempting to answer regex-questions was the best method to learn them.
In particular I found the postings by Gabor Grothendieck very helpful in
getting some degree of competence in this area. I see that his grep-related
postings still exceed my grep postings and I assure you that his will be
more sophisticated than my efforts. I recommend the MarkMail Rhelp mirror
interface as very useful in "mining" Rhelp for knowledge:
Gabor Grothendieck answers with either 'grep' pr 'regex' in their body:
http://markmail.org/search/?q=list%3Aorg.r-project.r-help+list%3Agrep+list%3Aregex+from%3A%22Gabor+Grothendieck
--
Happy searching;
David.
--
Sent from my phone. Please excuse my brevity.
On May 3, 2016 10:45:42 PM PDT, Steven Yen <syen04 at gmail.com> wrote:
Dear all
In the grep command below, is there a way to identify only "age" and
not "age2"? In other words, I like to greb "age" and "age2"
separately, one at a time. Thanks.
x<-c("abc","def","rst","xyz","age","age2")
x
[1] "abc" "def" "rst" "xyz" "age" "age2"
grep("age2",x)
[1] 6
grep("age",x) # I need to grab "age" only, not "age2"
[1] 5 6
David Winsemius
Alameda, CA, USA