[R] Regular expression problem

[Rolf Turner]

On 16/09/2009, at 9:58 AM, jim holtman wrote:

> try:
>
>> grep("n.*mytype",mystr)
> [1] 1
>
>
> with the [.] it is a class with a period.  '.*' match zero, or  
> more, characters.

Perhaps the OP wants

	grep("n[.].*mytype",mystr)

to insist that ``mystr'' contain the string ``n.'' (literal ``.'')
somewhere before the string ``mytype''.

	cheers,

		Rolf Turner
>
> On Tue, Sep 15, 2009 at 5:52 PM, Sebastien Bihorel
> <sebastien.bihorel at cognigencorp.com> wrote:
>> Dear R-users,
>>
>> I am trying to use the grep function to test whether a particular  
>> string is
>> of the form "n.../mydir/myfile.mytype.myext". Anything between n  
>> and mytype
>> could vary, and anything after mytype could vary. I tried to  
>> proceed by
>> steps to build my regular expression... but I do not really  
>> understand why
>> the last call of the following code do not work.
>>
>> Any help would be greatly appreciated.
>>
>> mystr <- "n.../mydir/myfile.mytype.myext"
>>
>> grep("mytype",mystr)
>> # returns 1
>>
>> grep("[.]*mytype",mystr)
>> # returns 1
>>
>> grep("n[.]*mytype",mystr)
>> # returns integer(0)
>>
>>
>> Sebastien
>>
>> ______________________________________________
>> 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.
>>
>
>
>
> -- 
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
>
> ______________________________________________
> 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.


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