Re: [R] newbie question about index

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Fri 01 Sep 2006 - 08:45:41 GMT

Here is an additional way:

model.matrix(~ factor(a) - 1)

On 9/1/06, Gabor Grothendieck <ggrothendieck@gmail.com> wrote:
> Try using outer:
>
> outer(1:3, a, "==")+0
>
>
>
>
> On 8/31/06, z s <flyhyena@yahoo.com.cn> wrote:
> > Hi,
> >
> > I am trying to convert a variable a = sample(1:3,100,rep = T) represents choices into a 3X100 dummy varible b with corresponding element set to 1 otherwise 0.
> > eg.
> >
> > a: 1 3 2 1 2 3 1 1....
> >
> > b: 1 0 0 1 0 0 1 1..
> > 0 0 1 0 1 0 0 0...
> > 0 1 0 0 0 1 0 0...
> >
> > Is there something like b[a] =1 existing? I could not figure this out myself.
> >
> >
> > ---------------------------------
> > Mp3疯狂搜-新歌热歌高速下
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> >
> >
> >
> > ______________________________________________
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> >
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> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> >
> >
>



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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. Received on Fri Sep 01 18:50:51 2006

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