[R] Applying a function to each element of an array

[Berton Gunter]

Well, since Sum(i=1 to i-n) =n*(n+1)/2, your loop simply gives
1/4*count*(count-1).
So if your matrix is A, A*(A-1)/4 is about the quickest way to get your
answer I think.

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box
 
 

> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Tim Smith
> Sent: Friday, October 07, 2005 11:48 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Applying a function to each element of an array
> 
> 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)
> }
>  
> 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,
>  
> Tim
> 
> 		
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