regular expression
Try this also:
grep("arg", "arg.symptom", value = TRUE, invert = TRUE)
character(0)
grep("arg", "liver.symptom", value = TRUE, invert = TRUE)
[1] "liver.symptom"
On Fri, Apr 1, 2011 at 1:33 PM, array chip <arrayprofile at yahoo.com> wrote:
Great. thank you Bernd! Learned a new thing here. John
________________________________
From: Bernd Weiss <bernd.weiss at uni-koeln.de>
Cc: r-help at r-project.org
Sent: Thu, March 31, 2011 6:19:25 PM
Subject: Re: [R] regular expression
Am 31.03.2011 21:06, schrieb array chip:
Ok then this code didn't do what I wanted. I want "not including
'arg' before '.symptom'", not individual letters of "arg", but rather
as a word.
Bill Dunlap suggested using invert=T, it works for single 1
condition, but not for 2 conditions here: not including "arg" before
".", but at the same time, does include ".symptom".
Any other suggestions would be appreciated
This does work (but I am by no means an expert in regex...). I am using
'negative lookbehind'[1] to define an expression like 'arg'.
grep('(?<!(arg))\\.symptom',"arg.symptom",value=T, perl = T)
character(0)
grep('(?<!(arg))\\.symptom',"liver.symptom",value=T, perl = T)
[1] "liver.symptom"
Bernd
[1] http://www.regular-expressions.info/lookaround.html
? ? ? ?[[alternative HTML version deleted]]
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