How to change legend size with matplotlib.pyplot

Question

Simple question here: I'm trying to get the size of my legend using matplotlib.pyplot to be smaller (i.e., the text to be smaller). The code I'm using goes something like this:

plot.figure() plot.scatter(k, sum_cf, color='black', label='Sum of Cause Fractions') plot.scatter(k, data[:, 0],  color='b', label='Dis 1: cf = .6, var = .2') plot.scatter(k, data[:, 1],  color='r',  label='Dis 2: cf = .2, var = .1') plot.scatter(k, data[:, 2],  color='g', label='Dis 3: cf = .1, var = .01') plot.legend(loc=2) 

Answer 1

You can set an individual font size for the legend by adjusting the prop keyword.

plot.legend(loc=2, prop={'size': 6}) 

This takes a dictionary of keywords corresponding to matplotlib.font_manager.FontProperties properties. See the documentation for legend:

Keyword arguments:

prop: [ None | FontProperties | dict ]     A matplotlib.font_manager.FontProperties instance. If prop is a      dictionary, a new instance will be created with prop. If None, use     rc settings. 

It is also possible, as of version 1.2.1, to use the keyword fontsize.

Answer 2

using import matplotlib.pyplot as plt

Method 1: specify the fontsize when calling legend (repetitive)

plt.legend(fontsize=20) # using a size in points plt.legend(fontsize="x-large") # using a named size 

With this method you can set the fontsize for each legend at creation (allowing you to have multiple legends with different fontsizes). However, you will have to type everything manually each time you create a legend.

(Note: @Mathias711 listed the available named fontsizes in his answer)

Method 2: specify the fontsize in rcParams (convenient)

plt.rc('legend',fontsize=20) # using a size in points plt.rc('legend',fontsize='medium') # using a named size 

With this method you set the default legend fontsize, and all legends will automatically use that unless you specify otherwise using method 1. This means you can set your legend fontsize at the beginning of your code, and not worry about setting it for each individual legend.

If you use a named size e.g. 'medium', then the legend text will scale with the global font.size in rcParams. To change font.size use plt.rc(font.size='medium')