[yt-dev] Implementing Backend Independent Plots: Pull Request 2294

Nathan Goldbaum nathan12343 at gmail.com
Mon Aug 1 10:45:40 PDT 2016 

On Mon, Aug 1, 2016 at 12:40 PM, Matthew Turk <matthewturk at gmail.com> wrote:

> Hi Nathan,
>
> On Mon, Aug 1, 2016 at 10:37 AM, Nathan Goldbaum <nathan12343 at gmail.com>
> wrote:
>
>>
>>
>> On Mon, Aug 1, 2016 at 12:17 PM, Matthew Turk <matthewturk at gmail.com>
>> wrote:
>>
>>> Hi Austin and Nathan,
>>>
>>> On Thu, Jul 28, 2016 at 10:51 AM, Nathan Goldbaum <nathan12343 at gmail.com
>>> > wrote:
>>>
>>>> Hi all,
>>>>
>>>> I just want to voice my main issues with the PR as it's currently
>>>> implemented. I've communicated this with Austin in private but want to make
>>>> sure this is all publicly written down so others can offer advice.
>>>>
>>>> Right now the PR makes it possible to do something like this:
>>>>
>>>>     import yt
>>>>     yt.toggle_interactivity()
>>>>
>>>>     slc = yt.SlicePlot(ds, 2, 'density')
>>>>     slc.show()
>>>>
>>>> and then have a GUI window pop up showing the plot.
>>>>
>>>> The toggle_interactivity() function queries matplotlib to get it's
>>>> current backend, and then uses that setting to choose a FigureCanvas
>>>> subclass to draw the plot onto.
>>>>
>>>> Unfortunately, matplotlib's support for creating working plots outside
>>>> of pyplot using a GUI backend is basically nil. For example, using Austin's
>>>> pull request with the MacOSX backend, I can't interact with the plot window
>>>> that pops up (mousing over it produces a beachball hang) and I need to exit
>>>> the python interpreter to close the window. If matplotlib is configured to
>>>> use the QT4 backend (e.g. most anaconda installs on linux), nothing shows
>>>> up except for a white window. In the TK backend, an exception gets printed
>>>> out. It *does* seem to work with the notebook backend though. I haven't
>>>> tried any of the other GUI backends.
>>>>
>>>> I didn't try manually testing Austin's pull request so the PR went
>>>> through a pass or two of review under the assumption that the GUI backends
>>>> were mostly working. I'd like to apologize to Austin for giving him
>>>> comments and suggestions that led to code improvements even though right
>>>> now I'm arguing that we should abandon the approach as implemented - I
>>>> could definitely have handled reviewing that PR with more empathy.
>>>>
>>>> Given that we have very little control over matplotlib's configuration
>>>> and which backend it will select at runtime, I don't think the API that
>>>> Austin has implemented will be very useful for most users. Most people will
>>>> either see a non-interactive plot window pop up that they can't close, no
>>>> plot at all, or get an error. At the matplotlib BOF at SciPy this year
>>>> there was some discussion about making matplotlib's backends more uniform
>>>> and exposing them better to the object oriented interface, but I don't
>>>> think it's straightforward right now to use them as we'd like to without
>>>> relying on pyplot somehow.
>>>>
>>>> That said, I know that Austin wants to use this for his own QT
>>>> application. I think the best thing to do there is to add an interface for
>>>> users who want to supply their own canvas objects to draw to. That way
>>>> anyone who wants to manage their own GUI event loop will still be able to
>>>> draw to a GUI canvas using yt's plotting code. I'd be very happy to spend
>>>> time getting this working.
>>>>
>>>> Alternatively, if we do want to keep the API Austin has worked out, I
>>>> think we'll need to manage our own GUI event loop, and write
>>>> backend-dependent support code to handle that. I think that this approach
>>>> will be difficult although certainly with a nice payoff - it's a very
>>>> commonly requested feature.
>>>>
>>>>
>>> I'm not sure I'm as pessimistic -- I've been experimenting with using
>>> the PR inside ipython with the matplotlib backend set, and it seems to
>>> work.  I think that it's reasonable to mandate that if we're running in an
>>> IPython session (not a notebook) where the thread model is set via
>>> --matplotlib= , that we should allow for this functionality.
>>>
>>>
>>
>> Sorry, can you clarify which backend you're using? I'm not sure there is
>> a "matplotlib" backend. For example, when I start IPython as you suggested,
>> I get the following error:
>>
>> [TerminalIPythonApp] CRITICAL | Bad config encountered during
>> initialization:
>> [TerminalIPythonApp] CRITICAL | The 'matplotlib' trait of a
>> TerminalIPythonApp instance must be any of [u'auto', u'gtk', u'gtk3',
>> u'inline', u'nbagg', u'notebook', u'osx', u'qt', u'qt4', u'qt5', u'tk',
>> u'wx'] or None, but a value of u'' <type 'unicode'> was specified.
>>
>
> I was using --matplotlib=qt
>
> I can't use the OSX one, but with that I was able to generate windows, and
> continue using the console.
>

I can confirm that works over here too, with both the QT4 and MacOSX
backend as well. Thanks for the suggestion! I wonder if there's a way to
get this to work without using --matplotlib...



>
>>
>>
>> In your running IPython session you should be able to get the current
>> backend by doing:
>>
>>      import matplotlib
>>      matplotlib.get_backend()
>>
>>
>>> Sorry that was a bit of a novel - wanted to distill my thinking on this
>>>> as clearly as possible.
>>>>
>>>> -Nathan
>>>>
>>>> On Thu, Jul 28, 2016 at 12:26 PM, Gilbert, Austin B <
>>>> agilbert39 at gatech.edu> wrote:
>>>>
>>>>> Hello All,
>>>>>
>>>>>      I recently submitted a pull request that enables all yt plots to
>>>>> utilize the various interactive backends matplotlib(mpl) has to offer. The
>>>>> primary benefit of this change is that it enables a few more features from
>>>>> mpl in jupyter notebooks, but it also creates the possibility for user
>>>>> created applications using python gui packages (pyqt, tk, cairo, etc.).
>>>>> However, enabling this feature outside of a notebook requires the user to
>>>>> configure matplotlib for the backend they are using, as well as
>>>>> implementing their own event loop for the application. I would like to hear
>>>>> from others if they feel this is to complex a task to put on the user, and
>>>>> also if they would utilize the feature.
>>>>>
>>>>>
>>>>> Austin Gilbert
>>>>>
>>>>> _______________________________________________
>>>>> yt-dev mailing list
>>>>> yt-dev at lists.spacepope.org
>>>>> http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org
>>>>>
>>>>>
>>>>
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