[R] finding files whose name does NOT contain a given charac

[(Ted Harding)]

On 02-Feb-10 15:18:28, Peter Dalgaard wrote:
> mauede at alice.it wrote:
>> Unluckily I dela with miRNA files whose name may contain the
>> character "*".
>> Because of the special meaning of "*" I have to remove it.
>> I found out how to make list.files() extract only those file
>> names which contain a "*"
>> Namely:
>> # list.files(pattern="\\*") 
>> 
>> Now I have to process all files whose name does NOT contain the
>> character "*".
>> I cannot have list.files() extract all files  whose name does NOT
>> match pattern="\\*
>> I tried using "^" in such a pattern but nothing is returned.
>> Any suggestion is welcome.
> 
> That'll be something like pattern="^[^*]*$" (untested, I don't think I
> have any filenames with "*" inside...)
> 
> Alternatively, you might try
> 
> allfiles <- list.files()
> withstar <- allfiles[grepl("\\*", allfiles)]
> nostar <- allfiles[!grepl("\\*", allfiles)]

Peter's first suggestion works. As often with regeular expressions,
"[...]" is your friend!

I have created dummy files "abcde"  "pq*st"  "uvwxyz", and then

  list.files()
  # [1] "abcde"  "pq*st"  "uvwxyz"
  list.files(pattern="[*]")
  # [1] "pq*st"
  list.files(pattern="^[^*]*$")
  # [1] "abcde"  "uvwxyz"

Ted.

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E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
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Date: 02-Feb-10                                       Time: 15:41:53
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