From: Berton Gunter <gunter.berton_at_gene.com>

Date: Sat 08 Oct 2005 - 05:21:01 EST

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Oct 08 05:26:05 2005

Date: Sat 08 Oct 2005 - 05:21:01 EST

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@stat.math.ethz.ch
**> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Tim Smith
**> Sent: Friday, October 07, 2005 11:48 AM
**> To: r-help@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
**>
**>
**> ---------------------------------
**>
**>
**> [[alternative HTML version deleted]]
**>
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*

>

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sat Oct 08 05:26:05 2005

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