import  matplotlib.pyplot as plt
import numpy as np

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'$really\ good$'])


# set line syles
a,= plt.plot(x, y1, label='linear line')
b,= plt.plot(x, y2, color='red', linewidth=1.0, linestyle='--', label='square line')

plt.legend(loc='upper right')

plt.show()

loc可用引數：

 'best' : 0,          
 '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,