How to plot thousands of circles quickly in Matplotlib?

To plot thousands of circles quickly in Matplotlib, we will have to use matplotlib.collections. In this case, we will use CircleCollection.

Steps

• Import the collections package from matplotlib along with pyplot and numpy.
• Set the figure size and adjust the padding between and around the subplots.
• Initialize variables "num" for number of small circles and "sizes" for sizes of circles.
• Create a list of circle patches.
• Add circle patch artist on the current axis.
• Set the margins of the axes.
• To display the figure, use show() method.

Example

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.collections as mc

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True

num = 1000
sizes = 50 * np.random.random(num)
xy = 10 * np.random.random((num, 2))

patches = [plt.Circle(center, size) for center, size in zip(xy, sizes)]

fig, ax = plt.subplots()

collection = mc.CircleCollection(sizes, offsets=xy, transOffset=ax.transData, color='green')
ax.add_collection(collection)

ax.margins(0.01)

plt.show()

Output

It will produce the following output