Repository navigation
Colorbar for imshow messes interactive cursor with masked data #15103
Description
Bug report
Adding a colorbar when the mappable is the result of imshow for a masked array changes the behavior of the interactive z-data cursor and triggers a UserWarning.
Code for reproduction
import numpy as np
import matplotlib.pyplot as plt
mask = np.zeros((4, 4), bool)
mask[:2] = True
A = np.ma.array(np.random.rand(4, 4), mask=mask)
fig, ax = plt.subplots(1, 1)
im = ax.imshow(A)
fig.colorbar(im)Actual outcome
~/.anaconda3/lib/python3.7/site-packages/matplotlib/ticker.py:632: UserWarning: Warning: converting a masked element to nan.
return '%-12g' % value
Expected outcome
Before adding the colorbar, the zdata cursor shows a blank ([]).
Matplotlib version
- Operating system: Linux
- Matplotlib version: 3.1.1
- Matplotlib backend (
print(matplotlib.get_backend())): Qt5Agg - Python version: 3.7.3
- IPython version: 7.2.0
- Other libraries:
Matplotlib installed from pip.
Activity
jklymak commentedon Aug 22, 2019
Any idea if this is a change of behaviour from previous versions? I know that the formatter changes to use the colorbar's formatter if its available, but not sure when that was introduced.
Descanonge commentedon Aug 23, 2019
I don't remember this warning ever coming up until recently.
After a bit of rollback, it seems this issue appeared with 3.1.0.
ImportanceOfBeingErnest commentedon Aug 23, 2019
Bisects to #12459