Grep command
On May 3, 2016, at 11:16 PM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote: 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