[R] how to return indexes

[Roger Bivand]

On Thu, 5 Sep 2002, demolombe wrote:

> Hello,
> 
> I wonder how to retreive indexes of data (and not data themseleves)
> 
> example: a vector x<-c(10,20,30,40,50,60)
>                a filter: f <- x>30 does retreive : 40,50,60
>                           f <- x[x>30] retreive
> false,false,false,true,true,true
> 
> i would retreive the indexes: 4,5,6  because the 4th, 5th and 6th values
> were selected
> 
> (this easy with matlab, but with R I know only sort(..., index.return=TRUE)
>  which does that
> 

which() ?

> x<-c(10,20,30,40,50,60)
> f <- x[x>30]
> f
[1] 40 50 60
> f <- which(x>30)
> f
[1] 4 5 6
> 

Roger

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no
and: Department of Geography and Regional Development, University of
Gdansk, al. Mar. J. Pilsudskiego 46, PL-81 378 Gdynia, Poland.

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