R help - Oct 2012 - listing the files in a directory using regular expressions

Hi Experts,
  
  This might be silly question that I am asking, but no way as I am new to
R.
I want to list the files in a directory using regular expression like
A_B*_C*.csv  etc.
How to make this possible in R ?
I tried like this list.files(dir=".", pattern="A_B*_C*.csv")
but this gives
no output, whereas list.files(.... pattern="*.csv") giving all the
.csv
files in the output, which I do not want.

Thanks
Sidda
   



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Hello,

Try the pattern "A_B.*_C.*\\.csv".

Hope this helps,

Rui Barradas
Em 14-10-2012 08:13, siddu479 escreveu:
> Hi Experts,
>    
>    This might be silly question that I am asking, but no way as I am new to
> R.
> I want to list the files in a directory using regular expression like
> A_B*_C*.csv  etc.
> How to make this possible in R ?
> I tried like this list.files(dir=".",
pattern="A_B*_C*.csv") but this gives
> no output, whereas list.files(.... pattern="*.csv") giving all
the .csv
> files in the output, which I do not want.
>
> Thanks
> Sidda
>     
>
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/listing-the-files-in-a-directory-using-regular-expressions-tp4646119.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
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On Sun, Oct 14, 2012 at 3:13 AM, siddu479 <onlyfordigitalstuff at
gmail.com> wrote:
> Hi Experts,
>
>   This might be silly question that I am asking, but no way as I am new to
> R.
> I want to list the files in a directory using regular expression like
> A_B*_C*.csv  etc.
> How to make this possible in R ?
> I tried like this list.files(dir=".",
pattern="A_B*_C*.csv") but this gives
> no output, whereas list.files(.... pattern="*.csv") giving all
the .csv
> files in the output, which I do not want.
>
1. Always read the help file:

?list.files

The argument name is path=, not dir=.

2. Also note that the pattern must be specified as a regular
expression and not a glob (as would be specified in a command line
shell).  For example, the B* part of the expression in your post means
0 or more B's.  It does not mean B followed by anything else.

If you want to use globs rather than regular expressions see

?glob2rx

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Hi Gabor,

  Thanks for your reply.. 
*glob2rx()* function works for my requirement to address global
pattern(using *) of files like we use in Unix shell.

  Sidda   



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On Sun, Oct 14, 2012 at 8:03 AM, siddu479 <onlyfordigitalstuff at
gmail.com> wrote:
>
> Hi Gabor,
>
>   Thanks for your reply..
> *glob2rx()* function works for my requirement to address global
> pattern(using *) of files like we use in Unix shell.
>
>   Sidda
>
Also Sys.glob may be useful here.