Matplotlib legend half-color line entry-CodePudding

Is there a way of drawing a multi-colored line for a single legend entry in Matplotlib?

For example, in the below figure, the line for entries Class 1 and two appear black to the left and gray to the right of the middle point.

CodePudding user response：

You can combine the handlers of each label via the tuple legend handler (

PS: If you have two subplots, you can combine the handles and the labels of both:

from matplotlib import pyplot as plt
from matplotlib.legend_handler import HandlerTuple
import numpy as np

fig, ax1 = plt.subplots()
ax1.plot(np.random.rand(2), color='black', ls='--', label='Class 1')
ax1.plot(np.random.rand(2), color='black', ls='-', label='Class 2')
ax2 = ax1.twinx()
ax2.plot(np.random.rand(2), color='.7', ls='--', label='Class 1')
ax2.plot(np.random.rand(2), color='.7', ls='-', label='Class 2')

handles1, labels1 = ax1.get_legend_handles_labels()
handles2, labels2 = ax2.get_legend_handles_labels()
labels = labels1   labels2
unique_labels = list(np.unique(labels))
combined_handles = [tuple([h for h, l in zip(handles1   handles2, labels) if l == label]) for label in unique_labels]

ax1.legend(handles=combined_handles, labels=unique_labels, handlelength=3,
           handler_map={tuple: HandlerTuple(ndivide=None, pad=0)})
plt.show()