Use either
> gsub(" ", "\\\\ ", "one two three") # double space after 'two'
[1] "one\\ two\\ \\ three"
or
> gsub(" ", "\\ ", "one two three", fixed=TRUE)
[1] "one\\ two\\ \\ three"
When 'fixed' is not TRUE then a backslash gives a special meaning to
the next character in the replacement argument.
E.g., "\\1" means to put the match corresponding to the first parenthesized
subpattern into the replacement and, when perl=TRUE "\\U" means to
capitalize the alphabetic characters in \\<digit> replacements. E.g.,
> gsub("([[:alpha:]])([[:alpha:]])", "\\2\\1", "one two three")
[1] "noe wto htere"
> gsub("( [[:alpha:]])", "\\U\\1", "one two three", perl=TRUE)
[1] "one Two Three"
Hence you need to have 2 backslashes in the replacement to put a backslash
in the ouput when fixed is FALSE.
You need to type 2 backslashes to put 1 backslash in a string, hence you need
to type 4 backslashes to have 2 in the replacement string.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> Of Nathan Skene
> Sent: Monday, December 17, 2012 9:45 AM
> To: r-help@r-project.org
> Subject: [R] Formatting a path for unix with gsub
>
> I have a path:
>
> path = "/nfs/users/nfs_n/ns9/
> Phenotype Analysis/Results/Run_AmplRatio_neg
> BinaryAll trained without akapn+tnik.csv"
>
> I wish to replace the spaces with "\ " so that it can be read by a system
> call to unix.
>
> Using gsub I try:
>
> > gsub(" ","\\ ",path)
> [1] "/nfs/users/nfs_n/ns9/Phenotype Analysis/Results/Run_AmplRatio_neg
> BinaryAll trained without akapn+tnik.csv"
>
> Various variations on this result in either adding no backslashes, or two at
> once. How do I just get one backslash inserted?
>
> Thanks
>
> [[alternative HTML version deleted]]
>
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> 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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