[R] string/character to number

[Berton Gunter]

Note: sub() returns a character vector not a numeric vector. as.numeric()
will convert it.

Slightly slicker and faster is: 2*(z=='a')-1   where z is your vector,
c('a','b','a','b')

Cheers,
Bert

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Jake Michaelson
Sent: Wednesday, June 22, 2005 2:46 PM
To: Jake Michaelson
Cc: R-help at stat.math.ethz.ch
Subject: Re: [R] string/character to number

Duh!

sub()

--Jake

On Jun 22, 2005, at 3:35 PM, Jake Michaelson wrote:

> I did a very quick search of the archive and couldn't find a readily
> available answer to this one:
>
> I'd like to convert, for example:
>
> c("a", "b", "a", "b")
>
> to
>
> c(1, -1, 1, -1)
>
> In the case of the first vector, it may be any length, but will always
> only have two unique values.  It must always be replaced by
> corresponding values of 1 and -1.
>
> Any thoughts?
>
> Thanks in advance,
>
> Jake
>
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