[R] sort file names in numerical order

[David Winsemius]

Another option:

require(gtools)
?mixedsort

 > mixedsort(fileNames)
[1] "A1"  "A2"  "A10" "B1"  "B2"  "B10"

--  
  David

On Jul 18, 2010, at 5:16 AM, Duncan Mackay wrote:

> Hi
>
> Yes it is possible- one way is:
>
> fileNames[order(sprintf("%02s", sub("[[:upper:]]","", fileNames)))]
> [1] "A1"  "B1"  "A2"  "B2"  "A10" "B10"
>
> Regards
>
> Duncan
>
> Duncan Mackay
> Department of Agronomy and Soil Science
> University of New England
> ARMIDALE NSW 2351
> Email home: mackay at northnet.com.au
>
> At 06:47 18/07/2010, you wrote:
>
>
>> > I get some file names by list.files().
>> > These names are in  alphabetical order.
>> > I want to change it to logical numeric  order.
>> > Example:
>> > > fileNames <- c("A10", "A1", "A2", "B1", "B2",  "B10")
>> > > sort(fileNames)
>> > [1] "A1"  "A10" "A2"  "B1"   "B10" "B2"
>> > I want to have:
>> > "A1"  "A2" "A10" "B1" "B2" "B10"
>> >
>> > Is  this possible?
>>
>> Greetings.  I see that you've gotten an elegant solution to your  
>> problem.
>> I've appended a poor-man's solution, which I generated more for my  
>> own
>> edification than for yours.
>>
>> -- Mike
>>
>>
>> ## modified file names, changed to exhibit sorting on letters
>> fileNames <- c("A10", "B10", "A1", "A2", "B1", "B2"); fileNames
>>
>> ## use regular expressions to pick off letters, numbers
>> fnLet <- gsub("(^[^0-9]+).*$", "\\1", fileNames); fnLet
>> fnNum <- gsub("^[^0-9]+(.*)$", "\\1", fileNames); fnNum
>>
>> ## need to force numeric sorting of the numbers
>> fnNum <- as.numeric(fnNum)
>>
>> ## find the order of the numbers, for later use in subsetting
>> fnNumOrd <- order(fnNum); fnNumOrd
>>
>> ## pack all the relevant information into a data frame, then select  
>> from that
>> fnPieces <- data.frame(fnLet, fnNum, fileNames,  
>> stringsAsFactors=FALSE);
>> fnPieces
>>
>> ## partial sort by numbers only (gives new df)
>> dfPartialSort <- fnPieces[fnNumOrd, ]; dfPartialSort
>>
>> ## find the order of the names, then select from new df with that
>> fnLetOrd <- order(dfPartialSort[, 1]); fnLetOrd
>> dfFullSort <- dfPartialSort[fnLetOrd, ]; dfFullSort
>>
>> ## the file names have "gone along for the ride", so pick them off  
>> now
>> sortedFileNames <- dfFullSort$fileNames; sortedFileNames
>>
>> ______________________________________________
>> 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.
>
> ______________________________________________
> 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.

David Winsemius, MD
West Hartford, CT