[R] boot() with an array-valued statistic?

Stephan Kolassa Stephan.Kolassa at gmx.de
Fri Dec 25 13:52:05 CET 2009


Dear guRus,

is there a version of boot() that deals with array data and array-valued 
statistics? For example:

foo <- array(rnorm(120),dim=c(3,5,8))
means <- apply(foo, MARGIN=c(2,3), FUN=mean)

means contains the means over the first dimension of foo: a 5x8 array. 
Now I would like to bootstrap this array, perhaps with something along 
the lines of some array.boot(), with an additional MARGIN parameter:

means.boot <- array.boot(foo, statistic=mean, MARGIN=c(2,3), R=1000)

I would like means.boot to contain (e.g., in analogy to boot(), in a 
component $t) an array of dimensions 1000x5x8, containing  componentwise 
means of sampled slices of foo, e.g., to get confidence intervals like this:

apply(means.boot$t,MARGIN=c(2,3),FUN=quantile,probs=c(.975,.025))

I have been playing around with plyr and various flavors of apply, and 
searching only yielded lots of hits for boot.array(), which is something 
completely different...

Any help would be greatly appreciated!

Cheers
Stephan




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