Spurious(?) all-NaN slice RuntimeWarning

[anntzer]

For example, the first example given in the README (using the 'scatter_density' method) currently emits

.../lib/python3.9/site-packages/mpl_scatter_density/generic_density_artist.py:77: RuntimeWarning: All-NaN slice encountered
  vmin = self._density_vmin(array)
.../lib/python3.9/site-packages/mpl_scatter_density/generic_density_artist.py:82: RuntimeWarning: All-NaN slice encountered
  vmax = self._density_vmax(array)

when run with numpy 1.20.1, matplotlib 3.3.0, mpl-scatter-density 0.7.

[wphilips]

The issue is caused by the call self.set_array(EMPTY_IMAGE) in base_image_artist.py(70);
EMPTY_IMAGE is an array with a single Nan entry
At some point this calls vmin = self._density_vmin(array) in generic_density_artist.py(77)
and this generates the warning.

I hope it can be fixed.

[ba05]

Any fix?

[ba05]

This is a numpy issue occuring in numpy\lib\nanfunctions.py
https://github.com/numpy/numpy/blob/v1.26.0/numpy/lib/nanfunctions.py#L236-L361

Can suppress the warning by wrapping the code section causing the warning with a warning ignore statement. See this post:
https://stackoverflow.com/questions/29688168/mean-nanmean-and-warning-mean-of-empty-slice