[R] Extracting a numeric prefix from a string

R user
Mon, 31 Jan 2005 09:33:37 -0000

You could use something like

y <- gsub('([0-9]+(.[0-9]+)?)?.*','\\1',x)
as.numeric(y)

But maybe there's a much nicer way.

Jonne.

On Mon, 2005-01-31 at 08:51 +0000, Mike White wrote:
> Hi
> Does anyone know if there is a function similar to as.numeric that will
> extract a numeric prefix from a string as in the following examples?
>
> x<-c(3, "abc", 5.67, "2.4a", "6a",
"6b", "2.4.a", 3, "4.2a")
> df.x<-data.frame(Code=x)
> x.str<-levels(df.x[,1])
> # required function  result
> 2.40 3.00 4.20 5.67 6.00 NA
>
> Thanks
> Mike White
>
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