R help - May 2011 - Applying "toupper" to only portions of text strings

Colleagues

Assume that I have a vector containing some text strings, some of which contain
a particular character.  I could like to apply "toupper" to the text
before the character.  For example (in this case, "|" is the
particular character):

ORIGINAL:
	TEXT	<- c("aaaa", "bbb|cc", "|ddd")

AFTER APPLICATION OF toupper:
	TEXT	<- c("AAAA", "BBB|cc", "|dddd")

I could loop through each element, strsplit at the character, apply toupper to
the first component, then paste each element together.  But, I hope that there
is a simpler means to accomplish this.

Thanks in advance.

Dennis


Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-866-PLessThan (1-866-753-7784)
www.PLessThan.com

Cute!
I don't think your proposed strategy is all that complicated, but see
the gsubfn package for a one-liner. In particular, check out

http://code.google.com/p/gsubfn/

where there is an example for your almost exact task.

-- Bert

On Thu, May 26, 2011 at 3:05 PM, Dennis Fisher <fisher at plessthan.com>
wrote:
> Colleagues
>
> Assume that I have a vector containing some text strings, some of which
contain a particular character. ?I could like to apply "toupper" to
the text before the character. ?For example (in this case, "|" is the
particular character):
>
> ORIGINAL:
> ? ? ? ?TEXT ? ?<- c("aaaa", "bbb|cc",
"|ddd")
>
> AFTER APPLICATION OF toupper:
> ? ? ? ?TEXT ? ?<- c("AAAA", "BBB|cc",
"|dddd")
>
> I could loop through each element, strsplit at the character, apply toupper
to the first component, then paste each element together. ?But, I hope that
there is a simpler means to accomplish this.
>
> Thanks in advance.
>
> Dennis
>
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-866-PLessThan (1-866-753-7784)
> www.PLessThan.com
>
> ______________________________________________
> 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.
>


-- 
"Men by nature long to get on to the ultimate truths, and will often
be impatient with elementary studies or fight shy of them. If it were
possible to reach the ultimate truths without the elementary studies
usually prefixed to them, these would not be preparatory studies but
superfluous diversions."

-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics
467-7374
http://devo.gene.com/groups/devo/depts/ncb/home.shtml

On May 27, 2011, at 00:05 , Dennis Fisher wrote:
> Colleagues
> 
> Assume that I have a vector containing some text strings, some of which
contain a particular character.  I could like to apply "toupper" to
the text before the character.  For example (in this case, "|" is the
particular character):
> 
> ORIGINAL:
> 	TEXT	<- c("aaaa", "bbb|cc", "|ddd")
> 
> AFTER APPLICATION OF toupper:
> 	TEXT	<- c("AAAA", "BBB|cc", "|dddd")
> 
How are you going to get that extra d in there? >;-)
> I could loop through each element, strsplit at the character, apply toupper
to the first component, then paste each element together.  But, I hope that
there is a simpler means to accomplish this.
No, I think that is pretty much the plan. It's a one-liner, though:
> sapply(strsplit(TEXT,"|",
fixed=T),function(x){paste(c(toupper(x[1]),x[-1]),collapse="|")})
[1] "AAAA"   "BBB|cc" "|ddd"  


OK, a _long_ one-liner...

-- 
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

Dennis -
     Here's one way, using a somewhat obscure feature of perl
regular expressions, i.e. the \U and \L escape characters which
modify the case of the strings they appear in:
> TEXT    <- c("aaaa", "bbb|cc", "|ddd")
>
sub('([a-z]*)(\\|?)([a-z]*)','\\U\\1\\2\\L\\3',TEXT,perl=TRUE)
[1] "AAAA"   "BBB|cc" "|ddd"

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu



On Thu, 26 May 2011, Dennis Fisher wrote:
> Colleagues
>
> Assume that I have a vector containing some text strings, some of which
contain a particular character.  I could like to apply "toupper" to
the text before the character.  For example (in this case, "|" is the
particular character):
>
> ORIGINAL:
> 	TEXT	<- c("aaaa", "bbb|cc", "|ddd")
>
> AFTER APPLICATION OF toupper:
> 	TEXT	<- c("AAAA", "BBB|cc", "|dddd")
>
> I could loop through each element, strsplit at the character, apply toupper
to the first component, then paste each element together.  But, I hope that
there is a simpler means to accomplish this.
>
> Thanks in advance.
>
> Dennis
>
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-866-PLessThan (1-866-753-7784)
> www.PLessThan.com
>
> ______________________________________________
> 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.
>

On Thu, May 26, 2011 at 6:05 PM, Dennis Fisher <fisher at plessthan.com>
wrote:
> Colleagues
>
> Assume that I have a vector containing some text strings, some of which
contain a particular character. ?I could like to apply "toupper" to
the text before the character. ?For example (in this case, "|" is the
particular character):
>
> ORIGINAL:
> ? ? ? ?TEXT ? ?<- c("aaaa", "bbb|cc",
"|ddd")
>
> AFTER APPLICATION OF toupper:
> ? ? ? ?TEXT ? ?<- c("AAAA", "BBB|cc",
"|dddd")
>
> I could loop through each element, strsplit at the character, apply toupper
to the first component, then paste each element together. ?But, I hope that
there is a simpler means to accomplish this.
>
Try this:
> library(gsubfn)
> gsubfn("^[^|]+", toupper, TEXT)
[1] "AAAA"   "BBB|cc" "|dddd"

The regular expression starts from the beginning of the string (i.e.  ^ ) and
includes any immediately following characters that are not | (i.e.  [^|]+ ).
-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com