Re: [Matplotlib-users] Trouble with contour plot

[Nikolaus R. <Nik...@ra...>]

Eric Firing <efi...@pu...> writes:
>> I don't know if there are any strict requirement on monotonicity for X
>> and Y, or if there are any cases where the plot is still valid even if
>> that property is violated.  If it is a requirement, then I agree that
>> there should be a check.
>
> For sensible output, it is a requirement.  Contour and contourf (like 
> imshow, pcolor, and pcolormesh) work with gridded data.  Gridding is the 
> responsibility of the user.  It can be done in many different ways, so 
> it makes sense to keep the gridding separate from the display of the 
> gridded data.
>
> If there is a check--and I am not convinced there should be--it should 
> provide only a warning.  It is perfectly reasonable for a person to take 
> a dataset and contour it even if the grid is not monotonic.  Sometimes 
> one wants to get a quick look at raw input, complete with errors.


I don't quite understand your last point. In my example, the
single jump from pi to -pi makes half of the plot constant while in
truth it is oscillatory. I would not say that this reflects the "raw
input" in any way, and I am not sure what one could learn from this plot
with a quick (or even prolonged) look.

Am I missing something? Is there some obvious connection between the
jump in Theta, the data, and the resulting plot? To me the plot looks
like unpredictable garbage, so I really don't understand how anyone
could want to do something like that...


Best,

   -Nikolaus

-- 
 »Time flies like an arrow, fruit flies like a Banana.«

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