Tim Smith wrote:
> Hi,
>
> I have a 7000x7000 matrix, and each element is an integer. For each element,
> I want to apply the function :
>
> wt <- 0
> for(q in 1:count){
> wt <- wt + 0.5^(q-1)
> }
>
This is not a function! Maybe you want
helper <- function(count) sum(0.5^((1:count)-1))
> I get the value of 'count' from the elements in the matrix , and want to
> store the corresponding 'wt' value for that element.
>
> I suppose I could loop through the matrix, and apply the function to each
> element but this would take a really really long time. Are there any quicker
> ways to get the same result?
>
> many thanks,
mapply(helper, yourmat)
gives you the elements of the matrix, as a vector. So you only must
reassemble as a matrix:
n <- nrow(yourmat)
p <- ncol(yourmat)
matrix( mapply(helper, yourmat), n, p)
Kjetil
>
> Tim
>
>
> ---------------------------------
>
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