matplotlib contours 等高线图

import matplotlib.pyplot as plt
import numpy as np

def f(x,y):
    return (1 - x/2 + x**5 + y**3) * np.exp(-x**2 - y**2)

n = 256
x = np.linspace(-3,3,n)
y = np.linspace(-3,3,n)
X,Y = np.meshgrid(x,y)

# use plt.contourf to filling contours
# X,Y and value for (X,Y) point
plt.contourf(X,Y,f(X,Y),8,alpha=0.75,cmap=plt.cm.hot)

# user plt.contourf to add contour lines
C = plt.contour(X,Y,f(X,Y),8,colors='black',linewidth=.5)

# adding label
plt.clabel(C,inline=True,fontsize=10)

plt.xticks(())
plt.yticks(())

plt.show()