gregexpr (PR#9965)

If you want all the matches (including overlaps) then you could try one
of these:
gregexpr("(?=3Dabab)","ababab",perl=3DTRUE)
[[1]]
[1] 1 3
attr(,"match.length")
[1] 0 0
gregexpr("ab(?=3Dab)","ababab",perl=3DTRUE)
[[1]]
[1] 1 3
attr(,"match.length")
[1] 2 2

The book "Mastering Regular Expressions" by Jeffrey Friedl has a lot of
detail on the hows and whys of regular expression matching.

--=20
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
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-----Original Message-----
From: r-devel-bounces at r-project.org=20
[mailto:r-devel-bounces at r-project.org] On Behalf Of=20
dolanp at science.oregonstate.edu
Sent: Wednesday, October 10, 2007 8:36 AM
To: r-devel at stat.math.ethz.ch
Cc: R-bugs at biostat.ku.dk
Subject: [Rd] gregexpr (PR#9965)
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Full_Name: Peter Dolan
Version: 2.5.1
OS: Windows
Submission from: (NULL) (128.193.227.43)
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gregexpr does not find all matching substrings if the=20
substrings overlap:
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gregexpr("abab","ababab")
[[1]]
[1] 1
attr(,"match.length")
[1] 4
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It does work correctly in Version 2.3.1 under linux.
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