Stop matplotlib repeating labels in legend

Question

Here is a very simplified example:

xvalues = [2,3,4,6]

for x in xvalues:
    plt.axvline(x,color=\'b\',label=\'xvalues\')

plt.legend()

Th

Answer 1

Based on answer https://stackoverflow.com/a/13589144/9132798 and https://stackoverflow.com/a/19386045/9132798 plt.gca().get_legend_handles_labels()[1] gives a list of names, it is possible to check if the label is already in the list while in the loop plotting (label= name[i] if name[i] not in plt.gca().get_legend_handles_labels()[1] else ''). For the given example this solution would look like:

import matplotlib.pyplot as plt

xvalues = [2,3,4,6]

for x in xvalues:
    plt.axvline(x,color='b',\
    label= 'xvalues' if 'xvalues' \
            not in plt.gca().get_legend_handles_labels()[1] else '')

plt.legend()

Which is much shorter than https://stackoverflow.com/a/13589144/9132798 and more flexible than https://stackoverflow.com/a/19386045/9132798 as it could be use for any kind of loop any plot function in the loop individually. However, for many cycles it probably slower than https://stackoverflow.com/a/13589144/9132798.