On Nov 13, 2009, at 9:13 AM, Giulio Di Giovanni wrote:
Dear all,
I cannot figure out how to solve a small problem (well, not for me),
surely somebody can help me in few seconds.
I have a series of strings in a vector X of the type "xxx", "yyy",
"zzz", "IgA", "IgG", "kkk", "IgM", "aaa".
I want to substitute every ENTIRE string beginning with "Ig" with "0".
So, I'd like to have "xxx", "yyy", "zzz", "0", "0", "kkk", "0", "aaa".
I can easily identify these strings with grep("^Ig", X), but if I
use this criterion in the sub() function (sub("^Ig", "0", X) I
obviously get "0A", "0G" etc.
I didn't expect to do it in this way and I tried with metacharacters
and regexps in order to grep and substitute the whole word (\b \>,
$). I don't post here my tryings, because they were obviously wrong.
Please can you help me?
x <- c("xxx", "yyy", "zzz", "IgA", "IgG", "kkk", "IgM", "aaa")
> sub("^Ig.*$", "0", x)
[1] "xxx" "yyy" "zzz" "0" "0" "kkk" "0" "aaa"
You need to have the search regex include the entire element and not
just the first couple of characters in order to replace the entire
element.
HTH,
Marc Schwartz
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