Re: [R] Variance

From: Andrew Robinson <A.Robinson_at_ms.unimelb.edu.au>
Date: Fri, 29 Apr 2011 08:24:01 +1000

A couple of points here ....

First, note that q doesn't increment in the code below. So, you're getting the same variance each time.

Second, note that (t$Rec1==input3 & t$Rec2==input4) evaluates to F?T or 0/1, and it's not clear from your code if that is what you intend.

Finally, it's much easier to work with commented, minimal, self-contained, reproducible code. Please consider submitting that with future questions.

I hope that this helps,

Andrew.

On Thu, Apr 28, 2011 at 05:58:24PM -0400, Dat Mai wrote:
> I'm trying to find the variance of various outputs in a matrix:
>
> for(l in 2:vl){
> for(o in 1:(l-1)){
>
> # Make sure the inputs are for the matrix "m"
> input3=rownames(v)[o]
> input4=colnames(v)[l]
>
> r=t[(t$Rec1==input3 & t$Rec2==input4),output]
>
> if(length(r)==0){
> r=t[(t$Rec1==input4 & t$Rec2==input3),output]
> }
>
> v[l,o]=var(q,na.rm=TRUE)
> v[o,l]=var(q,na.rm=TRUE)
> v[l,l]=var(q,na.rm=TRUE)
>
> }
> }
>
> Each output will yield multiple results, since each input length varies.
> I'm not sure if this is the right way to go about finding the variance of
> each pair, but this is what I've done.
> The main issue I have with this now is that the results in every box in the
> matrix yield the same exact number, even though that most likely shouldn't
> happen.
>
> The question is: "How would I find the variance of each pair of inputs?"
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.

-- 
Andrew Robinson  
Program Manager, ACERA 
Department of Mathematics and Statistics            Tel: +61-3-8344-6410
University of Melbourne, VIC 3010 Australia               (prefer email)
http://www.ms.unimelb.edu.au/~andrewpr              Fax: +61-3-8344-4599
http://www.acera.unimelb.edu.au/

Forest Analytics with R (Springer, 2011) 
http://www.ms.unimelb.edu.au/FAwR/
Introduction to Scientific Programming and Simulation using R (CRC, 2009): 
http://www.ms.unimelb.edu.au/spuRs/

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Received on Thu 28 Apr 2011 - 22:30:07 GMT

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