Styling part of label in legend in matplotlib

As silvado mentions in his comment, you can use LaTeX rendering for more flexible control of the text rendering. See here for more information: http://matplotlib.org/users/usetex.html

An example:

import numpy as npimport matplotlib.pyplot as pltfrom matplotlib import rc# activate latex text renderingrc('text', usetex=True)x = np.arange(10)y = np.random.random(10)z = np.random.random(10)fig = plt.figure()ax = fig.add_subplot(111)ax.plot(x, y, label = r"This is \textbf{line 1}")ax.plot(x, z, label = r"This is \textit{line 2}")ax.legend()plt.show()

Note the 'r' before the strings of the labels. Because of this the \ will be treated as a latex command and not interpreted as python would do (so you can type \textbf instead of \\textbf).

Write between '$$'to force matplotlib to interpret it.

import matplotlib.pyplot as pltplt.plot(range(10), range(10), label = "Normal text $\it{Italics}$")plt.legend()plt.show()

Adding more options to the above answer by fixing the issues with that answer, with OO interface not just the state-based pyplot interface, possibility to have spaces as part of the text, boldface option in addition to italics:

ax.legend(handles=legend_handles,          labels=legend_labels,          loc='upper right',          shadow=True,          fancybox=True,          facecolor='#C19A6B',          title="$\\bf{BOLDFACED\ TITLE}$",     # to boldface title with space in between          prop={'size': 12, 'style': 'italic'}  # properties for legend text         )

For italicized title with space in between replace the above title with,

 title="$\\it{ITALICIZED\ TITLE}$",