R help - Jan 2000 - How to change several elements of an array simultaneously?

I have a matrix `m' and two vectors `rs' and `cs'. I want to change
m at the
positions (rs[1], cs[1]), (rs[2], cs[2]), ... to 1. Obviously I can do that by
> m[rs + (cs-1) * dim(m)[1]] <- 1
but I would just be interested whether I am missing a more "intuitive"
way
of doing that.

Thanks in advance, Peter

____________________________________________________________

Peter Holzer                      phone: + 41 1 632 46 34
Seminar fuer Statistik, LEO C14   fax:   + 41 1 632 12 28
(Leonhardstr. 27)                  <holzer at stat.math.ethz.ch>
ETH (Federal Inst. Technology)
8092 Zurich                       http://www.stat.math.ethz.ch/~holzer/
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Peter Holzer <holzer at stat.math.ethz.ch> writes:
> I have a matrix `m' and two vectors `rs' and `cs'. I want to
change m at the
> positions (rs[1], cs[1]), (rs[2], cs[2]), ... to 1. Obviously I can do that
by
> 
> > m[rs + (cs-1) * dim(m)[1]] <- 1
> 
> but I would just be interested whether I am missing a more
"intuitive" way
> of doing that.
This one is probably a candidate for the title of "most often
overlooked feature":

    m[cbind(rs,cs)] <- 1

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   O__  ---- Peter Dalgaard             Blegdamsvej 3  
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