R help - Apr 2009 - toupper does not work in sub + regex

Hi, I don't know what I am doing wrong to the toupper does not seem
working in sub + regex.  The following returns 's' not the upper class
'S' as I expect:
 
sub("q_([a-z])[a-zA-Z]*",toupper('\\1'),"q_sviRaw")
 
Can someone tell me where I did wrong?
 
Thanks,
Richard

	[[alternative HTML version deleted]]

Thanks, Martin.  I did not realize that.  I never used perl compatible
regex before but seems now I should!

Richard

-----Original Message-----
From: Martin Morgan [mailto:mtmorgan at fhcrc.org] 
Sent: Monday, April 13, 2009 12:08 PM
To: Tan, Richard
Subject: Re: [R] toupper does not work in sub + regex

"Tan, Richard" <RTan at panagora.com> writes:
> Hi, I don't know what I am doing wrong to the toupper does not seem 
> working in sub + regex.  The following returns 's' not the upper
class
> 'S' as I expect:
>  
>
sub("q_([a-z])[a-zA-Z]*",toupper('\\1'),"q_sviRaw")
you're expecting toupper to be evaluated after substitution, but it is
evaluated before: toupper('\\1') ==> '\\1'. try

  sub("q_([a-z])[a-zA-Z]*",'\\U\\1',"q_sviRaw",
perl=TRUE)

  
> Can someone tell me where I did wrong?
>  
> Thanks,
> Richard
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org 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.
--
Martin Morgan
Computational Biology / Fred Hutchinson Cancer Research Center 1100
Fairview Ave. N.
PO Box 19024 Seattle, WA 98109

Location: Arnold Building M1 B861
Phone: (206) 667-2793

sub only handles replacement strings, not replacement functions.
Your code is the same as:

sub("q_([a-z])[a-zA-Z]*", '\\1', "q_sviRaw")

since toupper('\\1') has no alphabetics so its just literally
'\\1' and
the latter is what sub uses.

The gsubfn function in the gsubfn package can deal with replacement
functions:
> library(gsubfn)
> gsubfn("q_([a-z])[a-zA-Z]*", toupper, "q_sviRaw")
[1] "S"

See the home page: http;//gsubfn.googlecode.com, vignette and help page.

On Mon, Apr 13, 2009 at 11:54 AM, Tan, Richard <RTan at panagora.com>
wrote:
> Hi, I don't know what I am doing wrong to the toupper does not seem
> working in sub + regex. ?The following returns 's' not the upper
class
> 'S' as I expect:
>
>
sub("q_([a-z])[a-zA-Z]*",toupper('\\1'),"q_sviRaw")
>
> Can someone tell me where I did wrong?
>
> Thanks,
> Richard
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org 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.
>

You could also use \\U and \\L in the replacement
with perl=TRUE.  \\U "converts the rest of the replacement
to upper case" and \\L converts to lowercase. (By
"replacement" it means the parts of the replacement
that arise from parenthesized subpatterns in the pattern
argument, not the replacement argument itself.)  E.g.,
> sub("q_([a-z])[a-zA-Z]*", "\\U\\1\\L",
"q_sviRaw", perl=TRUE)
[1] "S"
> sub("q_([a-z])([a-zA-Z]*)", "\\U\\1 then \\L\\2",
"q_sviRaw",
perl=TRUE)
[1] "S then viraw"
> sub("q_([a-z])([a-zA-Z]*)", "\\U\\1 then \\2",
"q_sviRaw", perl=TRUE)
[1] "S then VIRAW"

Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com 

----------------------------------------------------------------------
[R] toupper does not work in sub + regex

Gabor Grothendieck ggrothendieck at gmail.com 
Mon Apr 13 18:26:12 CEST 2009

sub only handles replacement strings, not replacement functions.
Your code is the same as:

sub("q_([a-z])[a-zA-Z]*", '\\1', "q_sviRaw")

since toupper('\\1') has no alphabetics so its just literally
'\\1' and
the latter is what sub uses.

The gsubfn function in the gsubfn package can deal with replacement
functions:
> library(gsubfn)
> gsubfn("q_([a-z])[a-zA-Z]*", toupper, "q_sviRaw")
[1] "S"

See the home page: http;//gsubfn.googlecode.com, vignette and help page.

On Mon, Apr 13, 2009 at 11:54 AM, Tan, Richard <RTan at panagora.com>
wrote:
> Hi, I don't know what I am doing wrong to the toupper does not seem
> working in sub + regex.  The following returns 's' not the upper
class
> 'S' as I expect:
>
>
sub("q_([a-z])[a-zA-Z]*",toupper('\\1'),"q_sviRaw")
>
> Can someone tell me where I did wrong?
>
> Thanks,
> Richard