[R] Writing a function to return column position XXXX

[Dan Abner]

Hi everyone,

I am using Michael's approach (grepl()) to identify which columns
containing $ signs. I was hoping to incorporate this into a line of
code that would automatically 1) find which columns contain $ signs,
2) strip the $ and commas, and 3) convert the result to a numeric
vector.

I have the following:

col.id<-function(x) any(grepl("\\$",x))

cand2[which(sapply(cand2,col.id))]<-
	as.numeric(gsub("[$,]","",cand2[which(sapply(cand2,col.id))]))

However, I am doing something wrong: while the code correctly
identifies the columns containing $ signs, it also returns ALL NA for
those columns.

See my initial message for this thread for example data.

Any assistance is appreciated.

Thanks!

Dan


On Tue, Jan 24, 2012 at 9:04 AM, R. Michael Weylandt
<michael.weylandt at gmail.com> wrote:
> 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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