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plot label will not show up on legend if _ is used as first charcter in label #5200
Description
If the ASCII character 95 _ is used in as first character in a plot label, the label will not show up in the legend.
If only labels with _ in front are used, the following warning is given:
/opt/pkg/devel/python/3.4.3/lib/python3.4/site-packages/matplotlib-1.4.3-py3.4-linux-x86_64.egg/matplotlib/axes/_axes.py:475: UserWarning: No labelled objects found. Use label='...' kwarg on individual plots.
warnings.warn("No labelled objects found. "In order to test this bug, I tried a variety of matplotlib versions on Ubuntu and OS X.
- 0.99.1.1
- 1.1.0
- 1.3.1
- 1.4.3
All have the above behavior.
In order to reproduce the bug, I used the following minimal example:
import numpy as np
import matplotlib
import matplotlib.pyplot as plt
print(matplotlib.__version__)
x = np.linspace(-10, 10, 1024)
y = np.sin(x)
plt.plot(x,y, label="_abc")
plt.legend()
plt.show()Using r"_abc" instead does not solve the problem.
Activity
PrometheusPi commentedon Oct 6, 2015
The reason for this behavior comes from this if clause.
It seems to be the intended behavior as documented:
Sorry for the inconvenience. From my side, this issue can be closed.
tacaswell commentedon Oct 6, 2015
It is a surprising 'feature', but it has been that way for a long time and changing it would likely break a lot of code in the wild.
jhollowed commentedon Aug 31, 2021
this just sent me on a wild goose chase. All of my labels started with
__, so I kept getting "No handles with labels found to put in legend."This was very cryptic, and I could not solve this issue until finding this page. The error messaging on this should be improved.
jklymak commentedon Aug 31, 2021
The docs are relatively explicit about this https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.legend.html. Is there somewhere else you'd expect this information? If so, a PR would be most welcome.