matplotlib图例legend语法及设置的方法

#设置字体大小
fontsize : int or float or {‘xx-small', ‘x-small', ‘small', ‘medium', ‘large', ‘x-large', ‘xx-large'}

plt.legend(loc='best',frameon=False) #去掉图例边框
plt.legend(loc='best',edgecolor='blue') #设置图例边框颜色
plt.legend(loc='best',facecolor='blue') #设置图例背景颜色,若无边框,参数无效

plt.legend(loc='best',title='figure 1 legend') #去掉图例边框

plt.legend(loc=0, numpoints=1)
leg = plt.gca().get_legend() #或leg=ax.get_legend()
ltext = leg.get_texts()
plt.setp(ltext, fontsize=12,fontweight='bold') 

legend = ax.legend((rectsTest1, rectsTest2, rectsTest3), ('test1', 'test2', 'test3')) 
legend = ax.legend(loc='upper center', shadow=True, fontsize='x-large')
legend.get_frame().set_facecolor('red') #设置图例legend背景为红色
frame = legend.get_frame() 
frame.set_alpha(1) 
frame.set_facecolor('none') #设置图例legend背景透明 

ax1.legend_.remove() ##移除子图ax1中的图例
ax2.legend_.remove() ##移除子图ax2中的图例
ax3.legend_.remove() ##移除子图ax3中的图例

#主要是bbox_to_anchor的使用
box = ax1.get_position()
ax1.set_position([box.x0, box.y0, box.width , box.height* 0.8])
ax1.legend(loc='center', bbox_to_anchor=(0.5, 1.2),ncol=3)

import matplotlib.pyplot as plt
import numpy as np
x = np.random.uniform(-1, 1, 4)
y = np.random.uniform(-1, 1, 4)
p1, = plt.plot([1,2,3])
p2, = plt.plot([3,2,1])
l1 = plt.legend([p2, p1], ["line 2", "line 1"], loc='upper left')
 
p3 = plt.scatter(x[0:2], y[0:2], marker = 'D', color='r')
p4 = plt.scatter(x[2:], y[2:], marker = 'D', color='g')
# This removes l1 from the axes.
plt.legend([p3, p4], ['label', 'label1'], loc='lower right', scatterpoints=1)
# Add l1 as a separate artist to the axes
plt.gca().add_artist(l1)

import matplotlib.pyplot as plt
line1, = plt.plot([1,2,3], label="Line 1", linestyle='--')
line2, = plt.plot([3,2,1], label="Line 2", linewidth=4)
# 为第一个线条创建图例
first_legend = plt.legend(handles=[line1], loc=1)
# 手动将图例添加到当前轴域
ax = plt.gca().add_artist(first_legend)
# 为第二个线条创建另一个图例
plt.legend(handles=[line2], loc=4)
plt.show()