[R] Manipulate Data (with regular expressions)

[Kunzler, Andreas]

Thank you a lot,

I am almost done, but unfortunately I have to manipulate values like

x
220a1
220ab1
220a12 

to

y
220
220
220

Eventhough it is easy to macht a 3-digit number 
[0-9]{3}
I habe no idea how to mach everything except a 3-digit number in order to replace everything but the 3-digit number by ""

y <- gsub(RE for Everything but a 3-digit number, "", x) 

Maybe it ist possible to use the MATCH as the Replacer

y <- gsub([0-9]{3}, MATCH, x)

Thank you 

-----Ursprüngliche Nachricht-----
Von: Gabor Grothendieck [mailto:ggrothendieck at gmail.com] 
Gesendet: Dienstag, 8. Juli 2008 17:20
An: Kunzler, Andreas
Cc: r-help at r-project.org
Betreff: Re: [R] Manipulate Data (with regular expressions)

Try this:

x <- factor(c("220", "220a", "221", "221b", "B221"))
pat <- "[^0-9]+" # match non-digits
nums <- as.numeric(gsub(pat, "", x))
has.lets <- as.numeric(regexpr(pat, x) > 0)


On Tue, Jul 8, 2008 at 7:11 AM, Kunzler, Andreas <a.kunzler at bzaek.de> wrote:
> Dear Everyone,
>
>
>
> I try to automatically manipulate the data of a variable (class =
> factor) like
>
>
>
> x
>
> 220
>
> 220a
>
> 221
>
> 221b
>
> B221
>
>
>
> Into two variables (class = numeric) like
>
>
>
> x     y
>
> 220   0
>
> 220   1
>
> 221   0
>
> 221   1
>
> 221   1
>
>
>
> y has to carry the information about the class (number or string) of the
> former x-Variable.
>
>
>
> I could do it by hand like
>
>
>
> x[x == "220a"] <- 220
>
> y[x == "220a"] <- 1
>
>
>
> but x has way to many expressions.
>
>
>
> So I wondered if I could use a regular expression like OR ANY OTHER WAY
>
>
>
> x[x == [0-9]{3}a] <- regular expression
>
> y[x == [0-9]{3}] <- 1
>
>
>
>
>
> Thanks a lot
>
>
>
>
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>
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