对于每一个函数有自己的说明
import matplotlib.pyplot as plt
import numpy as np
# 设置数据
x = np.linspace(-3, 3, 50)
y1 = 2*x + 1
y2 = x**2
plt.figure()
# set x limits
plt.xlim((-1, 2))
plt.ylim((-2, 3))
# set new sticks
new_sticks = np.linspace(-1, 2, 5)
plt.xticks(new_sticks)
# set tick labels
plt.yticks([-2, -1.8, -1, 1.22, 3],
[r'$really\ bad$', r'$bad$', r'$normal$', r'$good$', r'$really\ good$'])
# 绘图
l1, = plt.plot(x, y1, label='linear line')
l2, = plt.plot(x, y2, color='red', linewidth=1.0, linestyle='--', label='square line')
# 显示各个函数的图例
plt.legend(loc='best')
# 允许修改函数自己的lable
# plt.legend(handles=[l1, l2], labels=['up', 'down'], loc='best')
# the "," is very important in here l1, = plt... and l2, = plt... for this step
"""legend( handles=(line1, line2, line3),
labels=('label1', 'label2', 'label3'),
'upper right')
The *loc* location codes are::
'best' : 0, (currently not supported for figure legends)
'upper right' : 1,
'upper left' : 2,
'lower left' : 3,
'lower right' : 4,
'right' : 5,
'center left' : 6,
'center right' : 7,
'lower center' : 8,
'upper center' : 9,
'center' : 10,"""
plt.show()