[Matplotlib-users] pyplot.contour() and filtered levels

Eric Firing efiring at hawaii.edu
Tue Sep 24 12:46:22 EDT 2019


I think this has been fixed, and the filtering is no longer done.  Would 
you try the current release, please?


On 2019/09/24 4:17 AM, Olivier B. wrote:
> I did another test, with the same code but by passing to matplotlib
> only the levels that are in the drawn area. My problem of line style
> shift disappears.
> Is it expected that when contour() filters level it will not filter
> the same lines of  linewidths, linestyles, and colors? Because they
> are not always the same number as the levels maybe? Or should this be
> considered a bug, at least for the case when the arrays have the same
> number of elements than levels? Could the documentation mention at
> least a warning about it?
> Le mar. 24 sept. 2019 à 14:15, Olivier B.
> <perso.olivier.barthelemy at gmail.com> a écrit :
>> At the switch to MPL 2.2 (from 1.5 i think), my calls to
>> pyplot.clabel() started throwing ValueError. This turned out to be
>> because the pyplot.contour() returned a ContourSet which had filtered
>> out the levels that were not displayed in the area of the data i am
>> trying to plot. As i build my list of level labels for the list of
>> levels that i pass to contour(), that list could contain levels that
>> had been filtered out by contour(), which throws a ValueError in
>> clabel(). so i also filtered my list of levels to label based on the
>> levels kept by the CountourSet.
>> Now, i get the impression that there is a similar issue for the
>> optional lists of line width, style, and color that we pass to
>> pyplot.contour.
>> If i move/zoom in a specific area of my data to draw isolines on it,
>> with the same python code everytime, that uses the same list of levels
>> based on the data of the whole area, and not levels based on the data
>> on the drawn area, depending on the area/zoom, the lines styles seem
>> to be shifted. As if levels were filtered out, but not the related
>> items of the other arrays, so styles apply to a different level.
>> Does someone have a hint about what's actually going on and how i
>> might work around it, or, if i'm lucky, if a version more recent than
>> 2.2.3 fixes this issue?
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