I wish to perform moving tiles bootstrap resampling on some gridded data 
meteorological data. I've many years experience with S-Plus, but it has 
no way to perform a moving-tiles bootstrap. Within R I've learned how to 
use quadratresample() with the spatstats package and would be happy to 
simply use empirical percentiles if generating the replicates were fast, 
but it isn't. So, I'd like to employ bootstrap tilting to generate my 
confidence intervals. On my machine (older Athlon, XP sp3, 4 GB) it took 
about 48 h to generate 5000 moving tiles replicates. But, the boot 
package contains boot.tilt and I should be able to do well enough with 
the statistics I need (mean and RMS) to get by with several hundred 
samples instead of several thousand.

I can certainly build a function that generates the statistic I want 
from a moving-tiles replicate. My problem is that the resampling process 
isn't as simple as boot.tilt() expects (I'm not simply resampling rows 
of a data frame). But, the function that does what I need doesn't fit 
into how boot.tilt() expects the resampling process to work. I can 
generate a string of replicates easily enough -- how might I wrap such a 
set of replicates into an object on which tilting could be performed 
absent the internal generation of the replicates themselves?

Kim Elmore
-- 

Kim Elmore, Ph.D. (CCM, PP SEL/MEL/Glider, N5OP, 2nd Class 
Radiotelegraph, GROL)

/"Human beings, who are almost unique in having the ability to learn 
from the experience/

/of//others, are also remarkable for their apparent disinclination to do 
so/."/-- Douglas Adams/


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