What I'm trying to do is control the fontsize of individual entries in a legend in pyplot. That is, I want the first entry to be one size, and the second entry to be another. This was my attempt at a solution, which does not work.

import numpy as np
import matplotlib.pyplot as pltx = np.arange(1,5,0.5)
plt.figure(1)
plt.plot(x,x,label='Curve 1')
plt.plot(x,2*x,label='Curve 2')
leg = plt.legend(loc = 0, fontsize = 'small')
leg.get_texts()[0].set_fontsize('medium')
plt.show()

My expectation is that the default size for all legend entries would 'small'. I then get a list of the Text objects, and change the fontsize for only a single Text object to medium. However, for some reason this changes all Text object fontsizes to medium, rather than just the single one I actually changed. I find this odd since I can individually set other properties such as text color in this manner.

Ultimately, I just need some way to change an individual entry's fontsize for a legend.

It appears that the font of each legend entry is managed by an instance of matplotlib.font_manager.FontProperties. The thing is: each entry doesn't have its own FontProperties... they all share the same one. This is verified by writing:

>>> t1, t2 = leg.get_texts()
>>> t1.get_fontproperties() is t2.get_fontproperties()
True

So if you change the size of the first entry, the size of the second entry is automatically changed along with it.

The "hack" to get around this is to simply create a distinct instance of FontProperties for each legend entry:

x = np.arange(1,5,0.5)
plt.figure(1)
plt.plot(x,x,label='Curve 1')
plt.plot(x,2*x,label='Curve 2')
leg = plt.legend(loc = 0, fontsize = 'small')t1, t2 = leg.get_texts()
# here we create the distinct instance
t1._fontproperties = t2._fontproperties.copy()
t1.set_size('medium')plt.show()

And now the sizing is correct: