Message-ID: <1317815812.96272.YahooMailClassic@web28215.mail.ukl.yahoo.com>
Date: 2011-10-05T11:56:52Z
From: Jannis
Subject: help with regexp
Dear list memebers,
I am stuck with using regular expressions.
Imagine I have a vector of character strings like:
test <- c('filename_1_def.pdf', 'filename_2_abc.pdf')
How could I use regexpressions to extract only the 'def'/'abc' parts of these strings?
Some try from my side yielded no results:
testresults <- grep('(?<=filename_[[:digit:]]_).{1,3}(?=.pdf)', perl = TRUE, value = TRUE)
Somehow I seem to miss some important concept here. Until now I always used nested sub expressions like:
testresults <- sub('.pdf$', '', sub('^filename_[[:digit:]]_', '' , test))
but this tends to become cumbersome and I was wondering whether there is a more elegant way to do this?
Thanks for any help
Jannis