Generate heatmap in Matplotlib

A heatmap can be created using Matplotlib and numpy.

Heatmap example

The histogram2d function can be used to generate a heatmap.

We create some random data arrays (x,y) to use in the program. We set bins to 64, the resulting heatmap will be 64x64. If you want another size change the number of bins.

import numpy as np
import numpy.random
import matplotlib.pyplot as plt
# Create data
x = np.random.randn(4096)
y = np.random.randn(4096)
# Create heatmap
heatmap, xedges, yedges = np.histogram2d(x, y, bins=(64,64))
extent = [xedges[0], xedges[-1], yedges[0], yedges[-1]]
# Plot heatmap
plt.clf()
plt.title('Pythonspot.com heatmap example')
plt.ylabel('y')
plt.xlabel('x')
plt.imshow(heatmap, extent=extent)
plt.show()

Want more practice on this without setting anything up? PyChallenge has graded plotting exercises that run in the browser, and the error message tells you what went wrong.

Result:

Matplotlib heatmap

The datapoints in this example are totally random and generated using np.random.randn()

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