[GRASS-dev] Re: [GRASS-SVN] r33673 - in grass/trunk/raster: . r.statistics2

[Hamish]

Glynn Clements wrote:
> I have no idea how you would compute diversity or mode for FP data
> (other than by sorting the entire set of values), or if this is even
> meaningful (if the values are physical quantities, then in the absence
> of rounding due to limited measuring precision, each value should
> theoretically be unique).

The quick answer is that you can't calculate diversity or mode for FP data
without depending on the quirks of FP precision or generalizing into
quantiles.

A more abstract answer is that you can, if you consider peaks in the
histogram, (like a gas chromatograph plot or radiance absorption peaks in
satellite imagery). A bimodal distribution would be more diverse than a 
simple Gaussian bell curve, etc. Spike with the biggest area under it would
be the mode?(??) Again there is the issue of quantile limits: how wide is a
real spike vs. what is sampling noise? what constitutes the spike vs 
bump threshold?


just an idea,
Hamish


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