Matplotlib.pyplot.contourf() in Python

Last Updated : 21 Apr, 2020

Matplotlib is a library in Python and it is numerical - mathematical extension for NumPy library. Pyplot is a state-based interface to a Matplotlib module which provides a MATLAB-like interface.

matplotlib.pyplot.contourf() Function

The contourf() function in pyplot module of matplotlib library is used to plot contours. But contourf draw filled contours, while contourf draws contour lines.

Syntax: matplotlib.pyplot.contourf(\*args, data=None, \*\*kwargs) Parameters: This method accept the following parameters that are described below:

X, Y: These parameter are the coordinates of the values in Z.

Z : This parameter is the height values over which the contour is drawn.

levels : This parameter is used to determine the numbers and positions of the contour lines / regions.

Returns: This returns the following:

c :This returns the QuadContourSet.

Below examples illustrate the matplotlib.pyplot.contourf() function in matplotlib.pyplot: Example #1:

Python3 1==

# Implementation of matplotlib function
import numpy as np
import matplotlib.pyplot as plt
from numpy import ma
from matplotlib import ticker, cm
 
N = 1000
x = np.linspace(-6.0, 6.0, N)
y = np.linspace(-7.0, 7.0, N)
X, Y = np.meshgrid(x, y)
 
Z1 = np.exp(X * Y)
z = 50 * Z1
z[:5, :5] = -1
z = ma.masked_where(z <= 0, z)
 
cs = plt.contourf(X, Y, z,
                  locator = ticker.LogLocator(),
                  cmap ="bone")

cbar = plt.colorbar(cs)

plt.title('matplotlib.pyplot.contourf() Example')
plt.show()

Output:

Example #2:

Python3 1==

# Implementation of matplotlib function
import matplotlib.pyplot as plt
import numpy as np
 
# invent some numbers, turning 
# the x and y arrays into simple
# 2d arrays, which make combining 
# them together easier.
x = np.linspace(-3, 15, 50).reshape(1, -1)
y = np.linspace(-3, 15, 20).reshape(-1, 1)
z = np.cos(x)*2 - np.sin(y)*2

# we no longer need x and y to
# be 2 dimensional, so flatten them.
x, y = x.flatten(), y.flatten()
 
cs = plt.contourf(x, y, z, 
                  hatches =['-', '/',
                            '\\', '//'],
                  cmap ='Greens',
                  extend ='both',
                  alpha = 1)

plt.colorbar(cs)

plt.title('matplotlib.pyplot.contourf() Example')
plt.show()