[R] regexpr virtue

[Gabor Grothendieck]

dot means any character and * repeats it for as many times
as possible so it replaces eveything (.*) up to the last
dot (\\.) with nothing.

On Wed, Jul 29, 2009 at 9:43 AM, Petr PIKAL<petr.pikal at precheza.cz> wrote:
> Thank you
>
> Gabor Grothendieck <ggrothendieck at gmail.com> napsal dne 29.07.2009
> 15:20:40:
>
>> Here are a couple of possibilities:
>>
>> sub(".*\\.", "", s)
>
> This seems to be the target. Can you be so kind and translate for me what
> it really does?
>
> ".* matches several dots?
> \\. what is this?
>
> I thought sub finds a match and replaces "replacement" in a string. But
> from this solution it seems that the command replaces all characters in a
> string with empty string and leave only value after three or two dots? Am
> I right?
>
> Best regards
> Petr
>
>
>
>>
>> library(gsubfn)
>> strapply(s, "[0-9]*$", simplify = c)
>>
>>
>>
>> On Wed, Jul 29, 2009 at 9:10 AM, Petr PIKAL<petr.pikal at precheza.cz>
> wrote:
>> > Hi all
>> >
>> > I have got something like that (actually those are column names)
>> >
>> > [51] "X19.2.300b...80"          "X19.2.400v...80" "X19.2.400b...80"
>> > "X19.2.300v...90"          "X19.2.300b...90"
>> > [56] "X19.2.400v...90"          "X19.2..400b..90" "X19.2.300v...100"
>> > "X19.2.300b...100"         "X19.2.400v...100"
>> >
>> > in character vector. I would like to get last n figures from this
>> > character vector but my regexpr unerstanding is inferior and I did not
>> > succeed.
>> > Please, is there anybody who can extract those n digits from end of
> each
>> > character string? If there were only 2 digits I could use substr but
> there
>> > can be one, two or three digits.
>> >
>> > I tried several variations of
>> >
>> > gsub("0:9$", "\\1" ,names(foto)[10])
>> >
>> > but either got whole string or an error.
>> >
>> > Best regards
>> > Petr
>> >
>> > ______________________________________________
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>> > 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.
>> >
>
>