R devel - Mar 2008 - invalid regular expression '[a-Z]'

Hi,

just curious, but does anyone know the source/reason of observing the
following error on OSX but not on WinXP and Linux?  I've tried with a
few different versions of R (v2.5.1, v2.6.1, v2.6.2, v2.7.0devel).
The locale does not seem to affect the error, i.e. I've tested a few
different and it is still only OSX that gives the error but not the
other two.
> regexpr("[a-Z]", "foo")
Error in regexpr(pattern, text, extended, fixed, useBytes) :
        invalid regular expression '[a-Z]'
> regexpr("[a-zA-Z]", "foo")
[1] 1
attr(,"match.length")
[1] 1
> regexpr("[A-z]", "foo")
[1] 1
attr(,"match.length")
[1] 1

At least now I know it that the safest is to use '[a-zA-Z]' (or
possibly '[[:alpha:]]').

/Henrik

On 05/03/2008 8:56 PM, Henrik Bengtsson wrote:
> Hi,
> 
> just curious, but does anyone know the source/reason of observing the
> following error on OSX but not on WinXP and Linux? 
Presumably in the locale you're using on OSX, "a" <
"Z" is false.  This
is the ascii sort order used in the C locale.  On my Windows box, "a"
<
"Z" is true, because it uses the English_Canada.1252 collation order.

Duncan Murdoch

  I've tried with a
> few different versions of R (v2.5.1, v2.6.1, v2.6.2, v2.7.0devel).
> The locale does not seem to affect the error, i.e. I've tested a few
> different and it is still only OSX that gives the error but not the
> other two.
> 
>> regexpr("[a-Z]", "foo")
> Error in regexpr(pattern, text, extended, fixed, useBytes) :
>         invalid regular expression '[a-Z]'
>> regexpr("[a-zA-Z]", "foo")
> [1] 1
> attr(,"match.length")
> [1] 1
>> regexpr("[A-z]", "foo")
> [1] 1
> attr(,"match.length")
> [1] 1
> 
> At least now I know it that the safest is to use '[a-zA-Z]' (or
> possibly '[[:alpha:]]').
> 
> /Henrik
> 
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