[R] regular expressions : extracting numbers

[jim holtman]

Is this what you want:

> x
 [1] "lema, rb 2%"   "rb 2%"         "rb 3%"         "rb 4%"
"rb 3%"         "rb 2%,mineuse"
 [7] "rb"            "rb"            "rb 12"         "rb"
"rj 30%"        "rb"
[13] "rb"            "rb 25%"        "rb"            "rb"
"rb"            "rj, rb"
> gsub("[^0-9]*([0-9]*)[^0-9]*", "\\1", x)
 [1] "2"  "2"  "3"  "4"  "3"  "2"  ""   ""   "12" ""   "30" ""   ""
"25" ""   ""   ""   ""
>


On 7/30/07, GOUACHE David <D.GOUACHE at arvalisinstitutduvegetal.fr> wrote:
> Hello all,
>
> I have a vector of character strings, in which I have letters, numbers, and symbols. What I wish to do is obtain a vector of the same length with just the numbers.
> A quick example -
>
> extract of the original vector :
> "lema, rb 2%" "rb 2%" "rb 3%" "rb 4%" "rb 3%" "rb 2%,mineuse" "rb" "rb" "rb 12" "rb" "rj 30%" "rb" "rb" "rb 25%" "rb" "rb" "rb" "rj, rb"
>
> and the type of thing I wish to end up with :
> "2" "2" "3" "4" "3" "2" "" "" "12" "" "30" "" "" "25" "" "" "" ""
>
> or, instead of "", NA would be acceptable (actually it would almost be better for me)
>
> Anyways, I've been battling with gsub() and things of the sort, but I'm drowning in the regular expressions, despite a few hours of looking at Perl tutorials...
> So if anyone can help me out, it would be greatly appreciated!!
>
> In advance, thanks very much.
>
> David Gouache
> Arvalis - Institut du Végétal
> Station de La Minière
> 78280 Guyancourt
> Tel: 01.30.12.96.22 / Port: 06.86.08.94.32
>
> ______________________________________________
> R-help at stat.math.ethz.ch 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 you are trying to solve?