Re: [Geotools-devel] Quantile classification oddities

[Andrea A. <aa...@op...>]

Jody Garnett ha scritto:
> Andrea Aime wrote:
>> Well, since I have a customer that needs this, and there seems to be 
>> no agreement (or lack of interest) on what to do, I'll roll a custom 
>> variant of the quantile algorithm inside GeoServer that does what I 
>> suggested, set apart the flat areas of the histogram in their own 
>> classes when they are big enough (say, half of a standard sized 
>> class?), and try to build classes with the expected size for the rest 
>> of the values.
> That sounds fine; why not just update the geotools implementation? ie we 
> found something that is a mistake (two categories with the same (0,0) 
> range) can we fix it?

Because in the last mail you proposed to fix it in ways I could not
see how to implement in a general way when there are multiple
areas of the data histogram that are flat (you suggested to try
and keep the intervals equal size and change the number of intervals,
or to force the number of intervals and accept the number of
items could be not equal).

>> I'd like to avoid that, but I see no way to do so without introducing 
>> extra parameters that would break all existing callers of the current 
>> quantile function...
> So far you have some style generation code; and it probably would die on 
> the case you describe anyways... if I cared to have specific 
> functionality I would have provided test cases. Lets rock and roll...

Sorry, this was meant to be an hour long fix and it already
took me an afternoon in mail exchanges only, time out for me.
I worked around it in the style generation code GeoServer side.

Cheers
Andrea