Thank you for the swift response. It looks like the code works the same way
with or without the "\\" in either the search string: { "\\_+" or "_+" } or
the replacement string: { "\\." or "." }. I tested this in Windows and
Linux (although we're still on R 2.4.1 in Linux). It's not clear to me why
I can use either two slashes or no slash safely, but not one slash, and it
makes me vaguely uneasy. Obviously, I need to review regular expressions,
but my usual sources, such as http://perldoc.perl.org/perlre.html, don't
seem to address this issue. I wonder whether there's a good document
explaining this.
-- TMK --
212-460-5430 home
917-656-5351 cell
>From: Uwe Ligges <[EMAIL PROTECTED]>
>To: Talbot Katz <[EMAIL PROTECTED]>
>CC: r-help@stat.math.ethz.ch
>Subject: Re: [R] gsub warning message
>Date: Fri, 31 Aug 2007 18:04:39 +0200
>
>
>
>Talbot Katz wrote:
>>Hi.
>>
>>I am using R 2.5.1 on a Windows XP machine. Here is an example of a piece
>>of code I was running in older versions of R on the same machine. I am
>>looking for underscores and replacing them with periods. This result is
>>from R 2.4.1:
>>
>>>gsub ( "\\_+","\.","AAA_I")
>>[1] "AAA.I"
>>
>>Here is what I get in R 2.5.1:
>>
>>>gsub ( "\\_+","\.","AAA_I")
>>[1] "AAA.I"
>>Warning messages:
>>1: '\.' is an unrecognized escape in a character string
>>2: unrecognized escape removed from "\."
>>
>>I still get the same result, which is what I want, but now I get a warning
>>message. Am I actually doing something wrong that the previous versions
>>of R didn't warn me about? Or is this warning message unwarranted? Is
>>there a fully approved method for getting the same functionality? Thanks!
>
>Yes, correct usage is either
> gsub ( "\\_+", ".", "AAA_I")
>or
> gsub ( "\\_+", "\\.", "AAA_I")
>
>Uwe Ligges
>
>
>
>>-- TMK --
>>212-460-5430 home
>>917-656-5351 cell
>>
>>______________________________________________
>>R-help@stat.math.ethz.ch 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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