legend marker size matplotlib code example

Example 1: legend size matplotlib

plt.plot([1, 2, 3], label='Inline label')
plt.legend(loc=1, prop={'size': 16})

Example 2: change markersize in legend matplotlib

lgnd = plt.legend(loc="lower left", scatterpoints=1, fontsize=10)
lgnd.legendHandles[0]._sizes = [30]
lgnd.legendHandles[1]._sizes = [30]