Hello!
 
library(gsubfn)
test <- c('filename_1_def.pdf', 'filename_2_abc.pdf')
gsubfn("(.+_)([a-z]+)(\\.pdf)", "\\2", test)

Cheers!!
Albert-Jan


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All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?
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>________________________________
>From: Jannis <bt_jannis@yahoo.de>
>To: r-help@stat.math.ethz.ch
>Sent: Wednesday, October 5, 2011 1:56 PM
>Subject: [R] 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
>
>
>
>______________________________________________
>R-help@r-project.org mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
>
>
>
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