[QGIS-Developer] Quantile (Equal Count) broken or is data borked?

[Nyall Dawson]

On Sat, 2 Mar 2019 at 22:09, Paolo Cavallini <cavallini at faunalia.it> wrote:

> we also noticed that for large data sets (tens of thousands records)
> `Pretty breaks` classification behaves strangely: when clicking on
> Classify repeatedly, classes boundaries change by about 10% all the
> time, apparently in a random fashion.
> Unsure whether this is the same or a different issue.

Do you mean pretty breaks or natural breaks (Jenks)? Jenks has been
that way forever -- by design (for performance) it takes a random
sample of the layer and generates the breaks from that sample only.
The random samples is selected anew with each click of classify, which
results in the different breaks.

Nyall

> All the best.
> --
> Paolo Cavallini - www.faunalia.eu
> QGIS.ORG Chair:
> http://planet.qgis.org/planet/user/28/tag/qgis%20board/
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