In [1]:

    

import matplotlib.pyplot as plt
import numpy as np
%matplotlib inline


    

In [2]:

    

x     = np.linspace(-1.0, 1.0, 100, endpoint=True)
y     = np.linspace(-1.0, 1.0, 100, endpoint=True)
X, Y  = np.meshgrid(x,y)


    

In [3]:

    

func  = lambda x, y: x**2 - y**2


    

In [4]:

    

Z     = func(X,Y)


    

In [5]:

    

f,a = plt.subplots()
cs  = a.contourf(X,Y,Z)
cb = f.colorbar(cs, ax=a)


    

In [6]:

    

levels = [-0.5, 0.0, 0.5]
colors = ('C0', 'C1')
extend = 'neither'
alpha = 0.9


    

In [7]:

    

f,a = plt.subplots()
cs  = a.contourf(X,Y,Z, levels=levels, colors=colors, extend=extend, alpha=alpha)
cb = f.colorbar(cs, ax=a)