[GRASS-user] Module to calculate percentile within a moving window?

Glynn Clements glynn at gclements.plus.com
Mon Feb 21 00:04:55 EST 2011

Tristan Nunez wrote:

> I'm a new GRASS user, and need to calculate the percentile rank of a
> cell within a moving window. Specifically, from a raster of wildlife
> habitat quality (ranked from 1 to 100) at 100m resolution, I would
> like to find the percentile rank of each focal cell relative to all of
> its neighboring cells within 20km of the focal cell - with an analysis
> extent of the western United States.
> It looks like r.neighbors calculates other moving window statistics
> (but not percentile rank), and r.univar calculates percentile rank. Is
> there a module that does both, or a way to make r.univar calculate
> percentile rank within a moving window? Would there be a relatively
> simple way to script this?

Recent version of r.neighbors can calculate arbitrary quantiles with

	r.neighbors method=quantile quantile=...

Glynn Clements <glynn at gclements.plus.com>

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