On Nov 7, 2010, at 10:30 AM, David Winsemius wrote:


On Nov 7, 2010, at 10:15 AM, Dimitris Rizopoulos wrote:

Dear All,

I would appreciate any help with the following: given the vector 'x'

x <- c("Ass1", "Ass.s1", "Ass2", "Ass.s2")

I would like to pick up the positions where the character string contains "Ass" but does not contain "Ass.s", so for 'x' that would be positions 1 and 3.

> x[ grepl("Ass", x) & !grepl("Ass\\.s", x) ]
[1] "Ass1" "Ass2"

Or if locations were needed the:

> setdiff( grep("Ass", x) , grep("Ass\\.s", x) )
[1] 1 3


HTH;
--
David


I guess this could be programmed around grep() using a suitable regular expression, but I haven't managed to succeed.

Thanks in advance.

Best,
Dimitris

--
Dimitris Rizopoulos
Assistant Professor

David Winsemius, MD
West Hartford, CT

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David Winsemius, MD
West Hartford, CT

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