Matplotlib Pie Charts

Understand the idea

Use only a few non-negative parts and state what the whole represents. Percent labels show a share of the supplied total, not a percentage of some unstated population. Equal aspect keeps the circle undistorted. Avoid three-dimensional effects or exploded slices that overemphasise one group without a reason.

Where to try it

Run this complete script in a local virtual environment with Matplotlib installed (py -m pip install matplotlib). It uses a non-interactive backend and saves workshop.png in the current folder. The site shows a rendered example below; its text-only online runner does not display plot windows.

A worked example

import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(7, 4), layout="constrained")
ax.pie([12, 8, 5], labels=["HTML", "CSS", "Python"], autopct="%1.0f%%")
ax.set(title="Share of 25 demo registrations", aspect="equal")
fig.savefig("workshop.png", dpi=140)
plt.close(fig)
print("Saved workshop.png")

Read the result

The shares are 48%, 32%, and 20% of the stated total of 25 registrations.

Try one change

Draw the same values as bars and decide which version makes the comparison easier.