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hline at y=0 appears after setting yscale to log #8783
Description
Bug report
Bug summary
Calling ax.axhline(0) after setting the y-scale to log rescales the y-axis to make the horizontal line appear at 1e-300.
Code for reproduction
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.scatter([1], [1])
ax.set_yscale('log')
ax.axhline(0)
plt.show()Actual outcome
with the warning
/Users/dstansby/matplotlib/lib/matplotlib/axes/_base.py:3208: UserWarning: Attempted to set non-positive ylimits for log-scale axis; invalid limits will be ignored.
'Attempted to set non-positive ylimits for log-scale axis; '
Expected outcome
I would expect the horizontal line to be ignored, and axis limits to remain as they were originally.
Matplotlib version
- Operating System: OSX 10.12.5
- Matplotlib Version: master branch installed using pip
- Python Version: 3.6.1
Activity
[-]vline at y=0 appears after setting yscale to log[/-][+]hline at y=0 appears after setting yscale to log[/+]tacaswell commentedon Jun 20, 2017
On the other hand, you asked it to draw a line at 0 a it made a best-effort to do so. What does a line at a negative position do?
anntzer commentedon Jun 20, 2017
Do nothing, which is what happens when the call to scatter is not included.
OTOH this is fixed by #8537.
dstansby commentedon Jun 21, 2017
Trying a line at a negative position (
ax.axhline(-1)) results in exactly the same behavior as above.Changing the code to
ignores the hline completely, and just shows the single scatter point as it was before. In my opinion I think this should be the behavior of `ax.set_yscale('log') too. At the very least they should be consistent which I think is what #8537 is for.
dstansby commentedon Jul 26, 2017
Fixed by #8836