Re: [R] regular expression

From: array chip <>
Date: Thu, 31 Mar 2011 18:06:41 -0700 (PDT)

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


From: Peter Langfelder <>

Cc: Bernd Weiss <>; Sent: Thu, March 31, 2011 5:55:26 PM
Subject: Re: [R] regular expression

> Thanks Bernd! I tried your approach with my real example, sometimes it worked,
> sometimes it didn't. For example
> grep('[^(arg)]\\.symptom',"stomach.symptom",value=T)
> [1] "stomach.symptom"
> grep('[^(arg)]\\.symptom',"liver.symptom",value=T)
> character(0)
> I think both examples should return the text, but the 2nd example didn't.
> What was wrong here?

Operator error :) Since you exclude 'r' before the '.', liver.symptom does not match the pattern.


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