matplotlib - making labels for violin plots

Question

I usually make labels for bars in the following manner using parameter 'label' in the method 'bar'.

axes[0].bar(x, y, bar_width, label='abc')
axes[0].legend()

Now I'd like to plot violin plots and make label for each collection as follows, but it doesn't work since 'violinplot' doesn't have the parameter 'label'.

axes[0].violinplot(data1, label='abc1')
axes[1].violinplot(data2, label='abc2')

Can anyone help me out to make a label for each collection?

Answer 1

As it was mentioned in comment, some plots in matplotlib don't support legends. Documentation still provides a simple way to add custom legends for them: http://matplotlib.org/users/legend_guide.html#proxy-legend-handles

Main idea : add 'fake' objects, which can be not shown in the plot, then use it to form a handles list for legend method.

    import random
    import numpy as np
    import matplotlib.pyplot as pl
    import matplotlib.patches as mpatches
    from itertools import repeat

    red_patch = mpatches.Patch(color='red')
    # 'fake' invisible object

    pos   = [1, 2, 4, 5, 7, 8]
    label = ['plot 1','plot2','ghi','jkl','mno','pqr']
    data  = [np.random.normal(size=100) for i in pos]

    fake_handles = repeat(red_patch, len(pos))

    pl.figure()
    ax = pl.subplot(111)
    pl.violinplot(data, pos, vert=False)
    ax.legend(fake_handles, label)
    pl.show()