On Oct 30, 2010, at 11:13 PM, David Winsemius wrote:
On Oct 30, 2010, at 10:51 PM, Ulrich wrote:Hi,is it possible to easily change the return value for the grep function for cases where there is no match, for example the value 0 or "No" instead of integer (0) )?Seems like is should be pretty easy. Test for length(grep(...)) == 0 or equivalently !length(grep(...))> gvec <- function(patt, x) sapply (x, function(y) if ( ! length(grep(patt, y)) ) {"No"} else {grep(patt, y)} )> gvec("b", c("abc", "abc\n")) abc abc\n 1 1 > gvec("\n", c("abc", "abc\n")) abc abc\n "No" "1"
It later occurred to me that you might only want the alternate behavior when no matches were present:
gvec2 <- function(patt, x) if ( !length(grep(patt, y)) ) {0} else {grep(patt, y)}
> gvec2 <- function(patt, x) if ( length(grep(patt, x))==0 ) {0} else {grep(patt, x)}
> grep("\n", c("abc", "abc\n"))
[1] 2
> gvec2("\n", c("abc", "abc"))
[1] 0
-- David Winsemius, MD West Hartford, CT
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