R help - Sep 2008 - Pattern match in R

I want to make sure this piece of code I wrote is doing what I want it to do.

ll<-function(string)
{
	grep(string,dir(),value=T)
}


subdir = ll("Coverage_[1-9][0-9]$")

I basically wrote a little function that would grab all the files of form
Coverage_[0-99]

The way I wrote it, will it grab Coverage_5 or does it have to have 2
numbers (10-99)?

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> I want to make sure this piece of code I wrote is doing what I want it 
to do.
> 
> ll<-function(string)
> {
>    grep(string,dir(),value=T)
> }
> 
> 
> subdir = ll("Coverage_[1-9][0-9]$")
> 
> I basically wrote a little function that would grab all the files of 
form
> Coverage_[0-99]
> 
> The way I wrote it, will it grab Coverage_5 or does it have to have 2
> numbers (10-99)?
This is straightforward to test.
filenames <- paste("Coverage", 0:99, sep="_")
grep("Coverage_[1-9][0-9]$", filenames, value=TRUE)

This returns:
[1] "Coverage_10" "Coverage_11" "Coverage_12"
"Coverage_13"
 [5] "Coverage_14" "Coverage_15" "Coverage_16"
"Coverage_17"
...
[89] "Coverage_98" "Coverage_99"

If you want all the files (Coverage_0 through to coverage_99), try this 
instead:
grep("Coverage_[0-9]{1,2}$", filenames, value=TRUE)

You may wish to take a look at the Repetition section on this page:
http://www.regular-expressions.info/quickstart.html

Regards,
Richie.

Mathematical Sciences Unit
HSL


------------------------------------------------------------------------
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On 30-Sep-08 14:36:04, bioinformatics_guy wrote:
> I want to make sure this piece of code I wrote is doing what
> I want it to do.
> 
> ll<-function(string)
> {
>       grep(string,dir(),value=T)
> }
> 
> subdir = ll("Coverage_[1-9][0-9]$")
> 
> I basically wrote a little function that would grab all the
> files of form Coverage_[0-99]
> 
> The way I wrote it, will it grab Coverage_5 or does it have to have 2
> numbers (10-99)?
I think you want "Coverage_[1-9]*[0-9]$", since your form will
only
match "Coverage_mn" where m is one of 1-9 and n is one of 0-9.
The "*" means "zero or any number of ... ".

Example (command-line grep in Linux):

grep 'Coverage_[1-9]*[0-9]$' << EOT
> Coverage
> Coverage_5
> Coverage_01
> Coverage_19
> Coverage_19q
> EOT
Coverage_5
Coverage_19

Note that this does not catch "Coverage_01" because "[1-9]"
does not include "0". Use "[0-9]" here as well if you need
this.

Hoping this helps,
Ted.


--------------------------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding at manchester.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 30-Sep-08                                       Time: 16:43:01
------------------------------ XFMail ------------------------------

Try this where ? signifies that the prior character is optional:

dir(pattern = "^Coverage_[1-9]?[0-9]$")


On Tue, Sep 30, 2008 at 10:36 AM, bioinformatics_guy
<wwwhitener at gmail.com> wrote:
>
> I want to make sure this piece of code I wrote is doing what I want it to
do.
>
> ll<-function(string)
> {
>        grep(string,dir(),value=T)
> }
>
>
> subdir = ll("Coverage_[1-9][0-9]$")
>
> I basically wrote a little function that would grab all the files of form
> Coverage_[0-99]
>
> The way I wrote it, will it grab Coverage_5 or does it have to have 2
> numbers (10-99)?
>
> --
> View this message in context:
http://www.nabble.com/Pattern-match-in-R-tp19743389p19743389.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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