R help - Jan 2012 - Writing a function to return column position XXXX

Hello everyone,

I am writing my own function to return the column index of all variables
(these are currently character vectors) in a data frame that contain a
dollar sign($). A small piece of the data look like this:

    can_sta can_zip ind_ite_con ind_uni_con AL 36106 $251,895.80 $22,874.43
AL 35802 $141,373.60 $7,100.00  AL 35201 $273,208.50 $18,193.66  AR
72404 $186,918.00
$25,391.00  AR 72217 $451,127.00 $27,255.23  AR 7.28E+08 $58,336.22 $5,293.82


So far I have:


col.id<-function(x) any(grep("$",x))
sapply(cand2,col.id)

However, this returns TRUE for all columns (even those that do not contain
the $).

Any assistance is appreciated.

Thank you,

Dan

	[[alternative HTML version deleted]]

Either

any(grepl("$",x, fixed = TRUE)) # You probably want grepl not grep
any(grepl("\\$",x) )
? regexpr # $ has a special value

Michael

PS -- Stop with HTML postings (seriously, it actually does mess up
what the rest of us see and I think it causes trouble for the archives
as well)

On Tue, Jan 24, 2012 at 8:49 AM, Dan Abner <dan.abner99 at gmail.com>
wrote:
> Hello everyone,
>
> I am writing my own function to return the column index of all variables
> (these are currently character vectors) in a data frame that contain a
> dollar sign($). A small piece of the data look like this:
>
> ? ?can_sta can_zip ind_ite_con ind_uni_con AL 36106 $251,895.80 $22,874.43
> AL 35802 $141,373.60 $7,100.00 ?AL 35201 $273,208.50 $18,193.66 ?AR
> 72404 $186,918.00
> $25,391.00 ?AR 72217 $451,127.00 $27,255.23 ?AR 7.28E+08 $58,336.22
$5,293.82
>
>
> So far I have:
>
>
> col.id<-function(x) any(grep("$",x))
> sapply(cand2,col.id)
>
> However, this returns TRUE for all columns (even those that do not contain
> the $).
>
> Any assistance is appreciated.
>
> Thank you,
>
> Dan
>
> ? ? ? ?[[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.

On 01/24/2012 03:49 PM, Dan Abner wrote:
> Hello everyone,
> 
> I am writing my own function to return the column index of all variables
> (these are currently character vectors) in a data frame that contain a
> dollar sign($). A small piece of the data look like this:
> 
>     can_sta can_zip ind_ite_con ind_uni_con AL 36106 $251,895.80 $22,874.43
> AL 35802 $141,373.60 $7,100.00  AL 35201 $273,208.50 $18,193.66  AR
> 72404 $186,918.00
> $25,391.00  AR 72217 $451,127.00 $27,255.23  AR 7.28E+08 $58,336.22
$5,293.82
> 
> 
> So far I have:
> 
> 
> col.id<-function(x) any(grep("$",x))
> sapply(cand2,col.id)
> 
> However, this returns TRUE for all columns (even those that do not contain
> the $).
> 
> Any assistance is appreciated.
One option is to use fixed = TRUE in the call to grep(). See ?grep.

BR,
-- 
Mikko Korpela
Aalto University School of Science
Department of Information and Computer Science