[Rd] regex to match word boundaries

Gabor Grothendieck ggrothendieck at myway.com
Thu Dec 2 03:05:59 CET 2004

Can someone verify whether or not this is a bug.

When I substitute all occurrence of "\\B" with "X"
R seems to correctly place an X at all non-word boundaries
(whether or not I specify perl) but "\\b" does not seem to
act on all complement positions:

> gsub("\\b", "X", "abc def") # nothing done
[1] "abc def"
> gsub("\\B", "X", "abc def") # as expected, I think
[1] "aXbXc dXeXf"
> gsub("\\b", "X", "abc def", perl = TRUE) # not as expected
[1] "abc Xdef"
> gsub("\\B", "X", "abc def", perl = TRUE)  # as expected
[1] "aXbXc dXeXf"
> R.version.string  # Windows 2000
[1] "R version 2.0.1, 2004-11-27"

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