hi: use the fact that Var(x) = E(x^2) - E(x)^2 so that you can still use
moments just like you did
for the mean.


On Thu, Oct 21, 2010 at 5:30 PM, Philippe Hensel
<Philippe.Hensel@noaa.gov>wrote:

> I am trying to create basic descriptive statistics for a spatial dataset
> using moving windows of variable sizes.
>
> I found the filter(dataset, rep(1/a,1)) very useful for obtaining averages
> for a given moving window size "a"
> (a is the window size within a column of data in a matrix - the filter is
> applied to all columns automatically)
>
> I could not find anything analogous for calculating variances over a moving
> window.  Is there one available?
> Otherwise, I'm slowly cranking away on making my own, but it's quite
> tedious!
>
> Thank you in advance for any insights!
>
> -Philippe
>
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