Re: [R] matrix indexing

From: Ben Rich <richmcb_at_gmail.com>
Date: Thu 18 Aug 2005 - 20:13:48 EST

Hi,

you might not consider this more elegant, but how about this

x[-apply(ind, 1, function(i) (i[1]-1)*nrow(x) + i[2])]

Ben

On 8/18/05, toka tokas <tokkass@yahoo.com> wrote:
> Dear R-users,
>
> I was wondering for the following:
>
> Let 'x' be a matrix and 'ind' and indicator matrix,
> i.e.,
>
> x <- array(1:20, dim = c(4, 5))
> ind <- array(c(1:3, 3:1), dim = c(3, 2))
>
> I'd like to get (as a vector) the elements of 'x'
> which are not indexed by 'ind'. Since negative indices
> are not allowed in index matrices I thought of using
> something like:
>
> x[ind] <- NA
> x[!is.na(x)]
>
> but are there any more elegant solutions.
>
> Thanks in advance,
> toka
>
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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 Received on Thu Aug 18 20:21:02 2005

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