matplotlib绘图4 图例

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-3,3,100)
y1 = 2*x + 1
y2 = x**2
#xy 的范围
plt.xlim((-1,2))
plt.ylim((-2,3))
#xy 描述
plt.xlabel('X')
plt.ylabel('Y')
#将x轴与y轴的数据保存在l1与l2中
l1, = plt.plot(x,y1,color='red',linewidth=1.0,linestyle='--')
l2, = plt.plot(x,y2,color='blue',linewidth=5.0,linestyle='-')
#设置图例
plt.legend(handles=[l1,l2],labels=['test1','test2'],loc='best')

new_ticks = np.linspace(-2,2,11)
plt.xticks(new_ticks)
plt.yticks([-1,0,1,2,3],
           ['level1','level2','level3','level4','level5'])
plt.show()