[R] Recursive function calls

[R. Michael Weylandt]

Note that this is a common enough case that Hadley provides for it
with the str_trim() function in his stringr package.

Best,
Michael

On Fri, Aug 3, 2012 at 12:02 PM, Bert Gunter <gunter.berton at gene.com> wrote:
> "Recursively loop over an object" is a pretty meaningless phrase,
> since it depends entirely on the structure of the object. For example,
> a character vector is an object, and there is no need for any sort of
> recursion to do what you want for it.
>
> The following regex example trims trailing "spaces" (see ?regex for an
> exact definition). Adapt it to whatever structure you like, probably
> with apply type functions.
>
>> x <- c("   ab   ","ab  \t  ","\t\t")
>> x
> [1] "   ab   " "ab  \t  "  "\t\t"
>> sub("[[:space:]]+$","",x)
> [1] "   ab" "ab"    ""
>
> But note also that (e.g. S3) methods and is.list or is.recursive may
> be useful in a more general approach, something like (where deSpace(x)
> is a function with the above sub() expression):
>
> nospace <- function(x){
> if(is.atomic(x))deSpace(x)
> else lapply(x, function(y)Recall(y))  ##?Recall for recursion
> }
>
> Note that this is completely untested, probably fails miserably and
> isn't what you want anyway, ...
> ;-)
> Good luck!
>
> Cheers,
> Bert
>
> On Fri, Aug 3, 2012 at 9:12 AM, Gene Leynes <gleynes at gmail.com> wrote:
>> My apologies, I know that this is not a new problem, but I'm not sure how
>> to find the answer
>>
>> I want to recursively loop over an object and trim trailing white space.
>> When I use this function on a list of data.frame I get output like this:
>> [1] "c(\"   many spaces   \", \"   many spaces   \")" "c(\"   many spaces
>> \", \"   many spaces   \")"
>>
>> What should I do to recombine the results?
>> If anyone has a good way to search for this type of question, that would be
>> appreciated.  I tried rseek.org with "recursive", but after wading though
>> all the rpart references I didn't find something that seemed to help with
>> this problem.
>>
>> Thank you very much.
>>
>>
>> trim <- function(x) {
>>     if(length(x)>1) sapply(x[1], trim)
>>     gsub("^[[:space:]]+|[[:space:]]+$", "", x)
>> }
>>
>> tempobj = '   many spaces   '
>> tempvec = c(tempobj, tempobj)
>> templist = list(tempvec, tempvec)
>> tempdf = data.frame(x = tempvec, y = tempvec)
>>
>> trim(tempobj)
>> trim(tempvec)
>> trim(templist)
>> trim(tempdf)
>>
>>
>>
>>
>>
>> Thank you,
>>    Gene Leynes
>> _____________________________________________
>> *Data Scientist*
>> *Mobile: 312-498-7702
>> **http://www.linkedin.com/in/geneleynes
>> *
>> <http://goog_598053156>*http://geneorama.com/ <http://geneorama.com/%20>*
>>
>>         [[alternative HTML version deleted]]
>>
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>
>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
> Phone: 467-7374
> Website:
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>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
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