[R] Finding indices with a certain property
Göran Broström
gb at stat.umu.se
Tue Dec 7 19:07:58 CET 1999
Quick answers to my question:
which(x < 0)
but also
> indices<-function(x)seq(along=x)[x]
> x <- c(1, -1, 3, 3, -2)
> indices(x<0)
[1] 2 5
from some.
The last one is essentially the definition of which, I think.
I had completely forgotten which (where?!?)
Thanks to Thomas Lumley, Jonathan Rougier, Martin Maechler,
Peter Dalgaard, Brian Ripley!
Göran
Original question:
> > I want the indices i for which x[i] < 0 (say):
> >
> > > x <- c(1, -1, 3, 3, -2)
> > > where.negative(x)
> > [1] 2 5
> >
> > Surely where.negative is something simple, but how?
--------------------------------------------------------------
Göran Broström
Department of Statistics tel: +46 90 786-5223
Umeå University fax: +46 90 786-6614
S-90187 Umeå, Sweden e-mail: gb at stat.umu.se
http://www.stat.umu.se/~gb ftp://capa.stat.umu.se
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