on 08/05/2008 08:55 PM [EMAIL PROTECTED] wrote:
Hi folks,
Can anyone enlighten me as to why I get the following when I search for
".csv" at the end of a string?
grep("\.csv$","Blah.csv",value=TRUE)
[1] "Blah.csv"
Warning messages:
1: '\.' is an unrecognized escape in a character string
2: unrecognized escape removed from "[\.]csv$"
R reference for regular expressions says
"Any metacharacter with special meaning may be quoted by preceding it
with a backslash. [...] The metacharacters in EREs are . \ | ( ) [ { ^
$ * + ?"
Am I missing something here? If "\." is not the right way to match a
period, can anyone tell me what is? I can't find anything on this in R
reference...
Look a little lower on the same page, where it notes:
Patterns are described here as they would be printed by cat: do remember
that backslashes need to be doubled when entering R character strings,
e.g. from the keyboard.
Thus:
grep("\\.csv$", "Blah.csv", value = TRUE)
Also see FAQ 7.37:
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-does-backslash-behave-strangely-inside-strings_003f
I'm using R 2.6 on Windows XP
Time to upgrade....2.7.1 is the current version.
HTH,
Marc Schwartz
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