[R] yet another vectorization question

[Adrian Dusa]

On Monday 30 January 2006 14:40, Philippe Grosjean wrote:
> Hello,
> Not exactly the same. By the way, why do you use do.call()? Couldn't you
> do simply:
> expand.grid(split(t(replicate(3, c(0, 1, NA))), 1:3))
> Best,
> Philippe Grosjean
>
> Jacques VESLOT wrote:
> > this looks similar:
> > do.call(expand.grid,split(t(replicate(3,c(0,1,NA))),1:3))

Sigh, what a pity. It is indeed not the same...
So close to a one-liner though.

I come back to my original question: is it possible to modify the content of a 
matrix, using apply on a different matrix?
In my original function, the slow part is:
## ...
for (k in 1:ncol(idk)) {
   end.row <- start.row + nrow(tt) - 1
   return.matrix[start.row:end.row, idk[ , k]] <- tt
   start.row <- end.row + 1
}
## ...

I'd like to use apply on the "idk" matrix (to get rid of the for loop) and 
write the contents of "tt" in the "result.matrix"...

Best,
Adrian

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Adrian DUSA
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