[R] why the "[^\\d]" is not equal to "[^0-9]" in R regular expression?

[William Dunlap]

Use perl=TRUE if you want \\d to mean something special (a digit) in a regular expression.

> identical(gregexpr(pattern="[^0-9]","+12345ty"), gregexpr(pattern="[^\\d]","+12345ty",perl=TRUE))
[1] TRUE

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of luofeiyu
> Sent: Sunday, December 29, 2013 3:42 AM
> To: R-help at r-project.org
> Subject: [R] why the "[^\\d]" is not equal to "[^0-9]" in R regular expression?
> 
> gregexpr(pattern="[^0-9]","+12345ty")
> [[1]]
> [1] 1 7 8
> attr(,"match.length")
> [1] 1 1 1
> attr(,"useBytes")
> [1] TRUE
> gregexpr(pattern="[^\\d]","+12345ty")
> [[1]]
> [1] 1 2 3 4 5 6 7 8
> attr(,"match.length")
> [1] 1 1 1 1 1 1 1 1
> attr(,"useBytes")
> [1] TRUE
> 
> why the pattern `[^\\d]` has no same effect as of `[^0-9]` ?
> 
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