Suspend plotting during fit

[ericpre]

Progress of the PR

• Suspend plotting when calling smart_fit to avoid error with event connections,
• add an changelog entry in the upcoming_changes folder (see upcoming_changes/README.rst),
• Check formatting changelog entry in the readthedocs doc build of this PR (link in github checks)
• ready for review.

Minimal example of the bug fix or the new feature

import hyperspy.api as hs

s = hs.datasets.eelsdb(title="Hexagonal Boron Nitride", spectrum_type="coreloss")[0]
ll = hs.datasets.eelsdb(title="Hexagonal Boron Nitride", spectrum_type="lowloss")[0]

s.set_microscope_parameters(beam_energy=300,
                            convergence_angle=0.2,
                            collection_angle=2.55)

s.add_elements(('B', 'N'))
m = s.create_model()
# m = s.create_model(ll=ll)
m.plot()
m.smart_fit()
m.enable_fine_structure()
m.smart_fit()

traceback:

Traceback (most recent call last):

  File "/home/eric/Dev/hyperspy/hyperspy/model.py", line 582, in update_plot
    self._model_line.update(render_figure=render_figure,

  File "/home/eric/Dev/hyperspy/hyperspy/drawing/signal1d.py", line 473, in update
    ydata = self._get_data()

  File "/home/eric/Dev/hyperspy/hyperspy/drawing/signal1d.py", line 431, in _get_data
    ydata = self.data_function(axes_manager=self.axes_manager,

  File "/home/eric/Dev/hyperspy/hyperspy/models/model1d.py", line 683, in _model2plot
    s = self.__call__(non_convolved=False, onlyactive=True)

  File "/home/eric/Dev/hyperspy/hyperspy/models/model1d.py", line 413, in __call__
    sum_ += component.function(axis)

  File "/home/eric/Dev/hyperspy/hyperspy/_components/eels_cl_edge.py", line 315, in function
    cts[bfs] = splev(

  File "/opt/miniconda3/lib/python3.8/site-packages/scipy/interpolate/fitpack.py", line 374, in splev
    return _impl.splev(x, tck, der, ext)

  File "/opt/miniconda3/lib/python3.8/site-packages/scipy/interpolate/_fitpack_impl.py", line 598, in splev
    raise ValueError("Invalid input data")

ValueError: Invalid input data


During handling of the above exception, another exception occurred:

Traceback (most recent call last):

  File "/home/eric/Dev/hyperspy/untitled1.py", line 23, in <module>
    m.smart_fit()

  File "/home/eric/Dev/hyperspy/hyperspy/models/eelsmodel.py", line 358, in smart_fit
    self._fit_edge(i, start_energy, **kwargs)

  File "/home/eric/Dev/hyperspy/hyperspy/models/eelsmodel.py", line 528, in _fit_edge
    self.remove_fine_structure_data(to_activate_fs)

  File "/home/eric/Dev/hyperspy/hyperspy/models/eelsmodel.py", line 597, in remove_fine_structure_data
    self.remove_signal_range(start, stop)

  File "/home/eric/Dev/hyperspy/hyperspy/decorators.py", line 107, in wrapper
    cm(self, *args, **kwargs)

  File "/home/eric/Dev/hyperspy/hyperspy/models/model1d.py", line 505, in remove_signal_range
    self._remove_signal_range_in_pixels(*indices)

  File "/home/eric/Dev/hyperspy/hyperspy/models/model1d.py", line 493, in _remove_signal_range_in_pixels
    self.update_plot()

  File "/home/eric/Dev/hyperspy/hyperspy/model.py", line 589, in update_plot
    self._disconnect_parameters2update_plot(components=self)

  File "/home/eric/Dev/hyperspy/hyperspy/model.py", line 563, in _disconnect_parameters2update_plot
    component.events.active_changed.disconnect(

  File "/home/eric/Dev/hyperspy/hyperspy/events.py", line 392, in disconnect
    raise ValueError("The %s function is not connected to %s." %

ValueError: The <bound method Signal1DLine._auto_update_line of <hyperspy.drawing.signal1d.Signal1DLine object at 0x7f0a51cf7cd0>> function is not connected to <hyperspy.events.Event: Event that triggers when the `Component.active` changes.: set()>.

It is surprising that with convolution with the low loss, smart_fit works fine when the model is plotted and without convolution, it raise an error (only when the model is plotted)! I am not sure if the ValueError("Invalid input data") is a red herring or not.
In any case, the plot should be suspended during calling smart_fit, because it slows down the fit, as it does for multifit

[codecov]

Codecov Report

Merging #2796 (8c7c936) into RELEASE_next_patch (2c61da2) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@                 Coverage Diff                 @@
##           RELEASE_next_patch    #2796   +/-   ##
===================================================
  Coverage               77.36%   77.37%           
===================================================
  Files                     202      202           
  Lines                   30105    30108    +3     
  Branches                 6579     6579           
===================================================
+ Hits                    23292    23295    +3     
  Misses                   5066     5066           
  Partials                 1747     1747           

Impacted Files	Coverage Δ
hyperspy/models/eelsmodel.py	57.76% <100.00%> (+0.34%)	⬆️

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[jlaehne]

lgtm