pick events don't work with twiny

ndbecker2 · January 30, 2018, 3:10pm

I find that pick events are fine until I add twiny. In that case, nothing
happens when clicking.

THe code outline is like:

fig, ax = plt.subplots()
ax2 = ax.twiny()
ax.semilogy(...)
fig.canvas.mpl_connect('pick_event', onpick)
ax2_xaxis = np.linspace (*ax.get_xlim(), endpoint=True,)/conversion
ax2.semilogy (ax2_xaxis, np.ones (len(ax2_xaxis)) * 1e-3, alpha=0)
ax2.set_xlabel(...)
...

removing all the lines about ax2 will restore pick function.

ben.v.root · January 30, 2018, 3:55pm

The problem is that the second axes is getting the pick events, because it
is on top of the first axes. This has been a problem for a long time, and
we haven't found a good solution for it.

Ben Root

···

On Tue, Jan 30, 2018 at 10:10 AM, Neal Becker <ndbecker2 at gmail.com> wrote:

I find that pick events are fine until I add twiny. In that case, nothing
happens when clicking.

THe code outline is like:

fig, ax = plt.subplots()
ax2 = ax.twiny()
ax.semilogy(...)
fig.canvas.mpl_connect('pick_event', onpick)
ax2_xaxis = np.linspace (*ax.get_xlim(), endpoint=True,)/conversion
ax2.semilogy (ax2_xaxis, np.ones (len(ax2_xaxis)) * 1e-3, alpha=0)
ax2.set_xlabel(...)
...

removing all the lines about ax2 will restore pick function.

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ndbecker2 · January 30, 2018, 4:15pm

Benjamin Root wrote:

The problem is that the second axes is getting the pick events, because it
is on top of the first axes. This has been a problem for a long time, and
we haven't found a good solution for it.

Ben Root

That was my guess. Is there any workaround?

···

On Tue, Jan 30, 2018 at 10:10 AM, Neal Becker > <ndbecker2 at gmail.com> wrote:

I find that pick events are fine until I add twiny. In that case,
nothing happens when clicking.

THe code outline is like:

fig, ax = plt.subplots()
ax2 = ax.twiny()
ax.semilogy(...)
fig.canvas.mpl_connect('pick_event', onpick)
ax2_xaxis = np.linspace (*ax.get_xlim(), endpoint=True,)/conversion
ax2.semilogy (ax2_xaxis, np.ones (len(ax2_xaxis)) * 1e-3, alpha=0)
ax2.set_xlabel(...)
...

removing all the lines about ax2 will restore pick function.

ben.v.root · January 30, 2018, 4:27pm

I seem to recall someone once messing around with the zorder of the axes
object, but I forget if that actually worked. Of course the other
workaround is to make the axes with the pickable objects be the twined axes.

Ben Root

···

On Tue, Jan 30, 2018 at 11:15 AM, Neal Becker <ndbecker2 at gmail.com> wrote:

Benjamin Root wrote:

> The problem is that the second axes is getting the pick events, because
it
> is on top of the first axes. This has been a problem for a long time, and
> we haven't found a good solution for it.
>
> Ben Root
>

That was my guess. Is there any workaround?

> On Tue, Jan 30, 2018 at 10:10 AM, Neal Becker > > <ndbecker2 at gmail.com> wrote:
>
>> I find that pick events are fine until I add twiny. In that case,
>> nothing happens when clicking.
>>
>> THe code outline is like:
>>
>> fig, ax = plt.subplots()
>> ax2 = ax.twiny()
>> ax.semilogy(...)
>> fig.canvas.mpl_connect('pick_event', onpick)
>> ax2_xaxis = np.linspace (*ax.get_xlim(), endpoint=True,)/conversion
>> ax2.semilogy (ax2_xaxis, np.ones (len(ax2_xaxis)) * 1e-3, alpha=0)
>> ax2.set_xlabel(...)
>> ...
>>
>> removing all the lines about ax2 will restore pick function.
>>

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jklymak1 · January 30, 2018, 5:08pm

Eric Firing took s stab at it a couple of years ago: ENH: allow changing the Axes sort order for event handling by efiring · Pull Request #2986 · matplotlib/matplotlib · GitHub

Obviously this is hard - if you stick a couple of artists on top of one another, deciding which one gets a mouse event is ambiguous.

I forget exactly how picking architecture works, but its seems *possible* to let each axes artist accept pick events. Then they can duke it out over who actually does something with it. But I?m not sure axes can actually do that at the present.

I also wonder if your `onpick` function can be made more sophisticated - I assume it knows what axis to look for picks in - maybe it could look in the twinned axis for a pick as well?

Cheers, Jody

···

On 30 Jan 2018, at 08:27, Benjamin Root <ben.v.root at gmail.com> wrote:

I seem to recall someone once messing around with the zorder of the axes object, but I forget if that actually worked. Of course the other workaround is to make the axes with the pickable objects be the twined axes.

Ben Root

On Tue, Jan 30, 2018 at 11:15 AM, Neal Becker <ndbecker2 at gmail.com <mailto:ndbecker2 at gmail.com>> wrote:
Benjamin Root wrote:

> The problem is that the second axes is getting the pick events, because it
> is on top of the first axes. This has been a problem for a long time, and
> we haven't found a good solution for it.
>
> Ben Root
>

That was my guess. Is there any workaround?

> On Tue, Jan 30, 2018 at 10:10 AM, Neal Becker > > <ndbecker2 at gmail.com <mailto:ndbecker2 at gmail.com>> wrote:
>
>> I find that pick events are fine until I add twiny. In that case,
>> nothing happens when clicking.
>>
>> THe code outline is like:
>>
>> fig, ax = plt.subplots()
>> ax2 = ax.twiny()
>> ax.semilogy(...)
>> fig.canvas.mpl_connect('pick_event', onpick)
>> ax2_xaxis = np.linspace (*ax.get_xlim(), endpoint=True,)/conversion
>> ax2.semilogy (ax2_xaxis, np.ones (len(ax2_xaxis)) * 1e-3, alpha=0)
>> ax2.set_xlabel(...)
>> ...
>>
>> removing all the lines about ax2 will restore pick function.
>>

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--
Jody Klymak

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sole · January 31, 2018, 7:31am

I'm using something on those lines since some time that works for me
since quite some time. Here is a code fragment:

??? self.ax = self.fig.add_axes([.15, .15, .75, .75], label="left")
??? self.ax2 = self.ax.twinx()
??? self.ax2.set_label("right")
??? # critical for picking!!!!
??? self.ax2.set_zorder(0)
??? self.ax2.set_autoscaley_on(True)
??? self.ax.set_zorder(1)
??? self.fig.sca(self.ax)

Best regards,

Armando

···

On 30/01/2018 17:27, Benjamin Root wrote:

I seem to recall someone once messing around with the zorder of the
axes object, but I forget if that actually worked. Of course the other
workaround is to make the axes with the pickable objects be the twined
axes.

joferkington · January 31, 2018, 1:43pm

If you know the artists you'd like to fire pick events for, you can work
around it in a few different ways. One option is to bind to mouse events
and handle firing off pick events in that callback.

Here's how mpldatacursor gets around the twinx/twiny issue:

github.com

joferkington/mpldatacursor/blob/master/mpldatacursor/datacursor.py#L658


      
              elif event.key == self.keybindings['previous']:
                  self._increment_index(-1)
          
          def _increment_index(self, di=1):
              """
              Move the most recently displayed annotation to the next item in the
              series, if possible. If ``di`` is -1, move it to the previous item.
              """
              if self._last_event is None:
                  return
          
              if not hasattr(self._last_event, 'ind'):
                  return
          
              event = self._last_event
              xy = pick_info.get_xy(event.artist)
          
              if xy is not None:
                  x, y = xy
                  i = (event.ind[0] + di) % len(x)
                  event.ind = [i]

Cheers,
-Joe

···

On Wed, Jan 31, 2018 at 1:31 AM, V. Armando Sol? <sole at esrf.fr> wrote:

On 30/01/2018 17:27, Benjamin Root wrote:
> I seem to recall someone once messing around with the zorder of the
> axes object, but I forget if that actually worked. Of course the other
> workaround is to make the axes with the pickable objects be the twined
> axes.
>

I'm using something on those lines since some time that works for me
since quite some time. Here is a code fragment:

            self.ax = self.fig.add_axes([.15, .15, .75, .75],
label="left")
            self.ax2 = self.ax.twinx()
            self.ax2.set_label("right")
            # critical for picking!!!!
            self.ax2.set_zorder(0)
            self.ax2.set_autoscaley_on(True)
            self.ax.set_zorder(1)
            self.fig.sca(self.ax)

Best regards,

Armando

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