[Matplotlib-users] updating contours

[Thomas Caswell]

Yes, please make a bug report.

I agree that it is not clear that collections is internal, but it _should_
be, that is a detail of how mpl stores the artists that need to be rendered
at draw time.

Because we store lines and collections in separate lists that get merged
and sorted based on z-order during the draw process we can get some
pathological rendering errors where errorbars have inconsistent layering.
In the near-ish (year?) there is likely to be a major refactoring to how
artists are stored internally to merge them into a single data structure.
We will provide back-compatible shims, but those will go away eventually so
the less code reaching in and touching them the better.

Tom

On Tue, Oct 27, 2015 at 9:49 AM Slavin, Jonathan <jslavin at cfa.harvard.edu>
wrote:

> Do you think it's worthy of a bug report?  It's not clear to me that the
> collections of the AxesSubplot should be considered as internal, though I
> do think that QuadContourSet objects should have a remove method in the
> same way that AxesImage and Line2D objects have.
>
> Jon
>
> On Tue, Oct 27, 2015 at 9:06 AM, Thomas Caswell <tcaswell at gmail.com>
> wrote:
>
>> That is a bug in something...
>>
>> On Tue, Oct 27, 2015, 08:53 Slavin, Jonathan <jslavin at cfa.harvard.edu>
>> wrote:
>>
>>> Tom,
>>>
>>> Do you mean something like:
>>> cs = ax.contour(...)
>>> .
>>> .
>>> .
>>> cs.remove()
>>> If so, that doesn't work:
>>> AttributeError: QuadContourSet instance has no attribute 'remove'
>>>
>>> Jon
>>>
>>> On Tue, Oct 27, 2015 at 7:48 AM, Thomas Caswell <tcaswell at gmail.com>
>>> wrote:
>>>
>>>> Please don't do ax.collections.pop(), it is better to keep a reference
>>>> to the object returned by contour and then using its remove method.
>>>>
>>>> The second way is safer as you will always remove the artist you think
>>>> you are removing and more future proof as the lists of artists (lines,
>>>> collections, ...) really should be considered internal details of mpl and
>>>> not accessed directly.
>>>>
>>>> Tom
>>>>
>>>> On Tue, Oct 27, 2015, 01:38 Slavin, Jonathan <jslavin at cfa.harvard.edu>
>>>> wrote:
>>>>
>>>>> Hi Mike,
>>>>>
>>>>> Yes, that's basically what I ended up doing.  I did
>>>>> ax.collections.pop()
>>>>> ax.contour(...)
>>>>>
>>>>> I'm not sure if there's a different (better?) way to remove the
>>>>> contours, but that works.
>>>>>
>>>>> By the way, it was not easy to discover that contours are collections
>>>>> (a LineCollection), though I guess it's not too hard to guess.  I think the
>>>>> docs could provide more information along these lines.
>>>>>
>>>>> Jon
>>>>>
>>>>> On Mon, Oct 26, 2015 at 11:07 AM, Michael Droettboom <
>>>>> mdroettboom at continuum.io> wrote:
>>>>>
>>>>>> You're correct that there is no equivalent -- contour is one of those
>>>>>> "computed" things that can't be directly updated from the original data.
>>>>>> You don't need to do a whole `cla()` though.  Removing the contour artist
>>>>>> and calling contour again should be sufficient.
>>>>>>
>>>>>> Mike
>>>>>>
>>>>>> On Fri, Oct 23, 2015 at 11:56 AM, Slavin, Jonathan <
>>>>>> jslavin at cfa.harvard.edu> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I'm looking at a series of images and want to include overplotted
>>>>>>> contours.  To update the image I just need to use the set_data() method of
>>>>>>> the AxesImage object.  However, as far as I can tell, there's nothing
>>>>>>> similar for the QuadContourSet object.  I tried set_array() but that didn't
>>>>>>> work.  Am I missing something?  Does anyone have any suggestions for how to
>>>>>>> update the contours?  Of course if necessary I could do a cla(), but that
>>>>>>> would be slow, I think.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Jon
>>>>>>> --
>>>>>>> ________________________________________________________
>>>>>>> Jonathan D. Slavin                 Harvard-Smithsonian CfA
>>>>>>> jslavin at cfa.harvard.edu       60 Garden Street, MS 83
>>>>>>> phone: (617) 496-7981       Cambridge, MA 02138-1516
>>>>>>> cell: (781) 363-0035             USA
>>>>>>> ________________________________________________________
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Matplotlib-users mailing list
>>>>>>> Matplotlib-users at python.org
>>>>>>> https://mail.python.org/mailman/listinfo/matplotlib-users
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Michael Droettboom
>>>>>> Continuum Analytics
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> ________________________________________________________
>>>>> Jonathan D. Slavin                 Harvard-Smithsonian CfA
>>>>> jslavin at cfa.harvard.edu       60 Garden Street, MS 83
>>>>> phone: (617) 496-7981       Cambridge, MA 02138-1516
>>>>> cell: (781) 363-0035             USA
>>>>> ________________________________________________________
>>>>>
>>>>> _______________________________________________
>>>>> Matplotlib-users mailing list
>>>>> Matplotlib-users at python.org
>>>>> https://mail.python.org/mailman/listinfo/matplotlib-users
>>>>>
>>>>
>>>
>>>
>>> --
>>> ________________________________________________________
>>> Jonathan D. Slavin                 Harvard-Smithsonian CfA
>>> jslavin at cfa.harvard.edu       60 Garden Street, MS 83
>>> phone: (617) 496-7981       Cambridge, MA 02138-1516
>>> cell: (781) 363-0035             USA
>>> ________________________________________________________
>>>
>>>
>
>
> --
> ________________________________________________________
> Jonathan D. Slavin                 Harvard-Smithsonian CfA
> jslavin at cfa.harvard.edu       60 Garden Street, MS 83
> phone: (617) 496-7981       Cambridge, MA 02138-1516
> cell: (781) 363-0035             USA
> ________________________________________________________
>
>
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