Python Matplotlib - Adding a Title to a Pie Chart

Pie Chart Title in Matplotlib

Pie charts are a popular way to represent data proportions visually. Adding a title to your pie chart helps provide context and make your visualization more informative. In this tutorial, we'll demonstrate how to add a title to a pie chart using Python's Matplotlib library.

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Basic Example: Adding a Title

The following example demonstrates how to create a pie chart and add a title:

import matplotlib.pyplot as plt

# Data for the pie chart
labels = ['Python', 'Java', 'C++', 'Ruby']
sizes = [45, 30, 15, 10]

# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%')

# Add title
plt.title('Programming Language Popularity')

# Show the plot
plt.show()

Explanation

1. The plt.pie() function is used to create the pie chart, with labels representing the categories and sizes defining their proportions.
2. The autopct parameter formats the percentages displayed on the chart.
3. The plt.title() function adds a title to the chart.

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Customizing the Title

You can customize the title's font size, color, and alignment using additional parameters in the plt.title() function.

import matplotlib.pyplot as plt

# Data for the pie chart
labels = ['Python', 'Java', 'C++', 'Ruby']
sizes = [45, 30, 15, 10]

# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%')

# Add customized title
plt.title('Programming Language Popularity', fontsize=16, color='blue', loc='left')

# Show the plot
plt.show()

Explanation

• fontsize: Sets the font size of the title (e.g., 16).
• color: Changes the title's color (e.g., 'blue').
• loc: Adjusts the title's alignment (options include 'left', 'center', and 'right').

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Example: Multiple Pie Charts with Titles

This example shows how to add titles to multiple pie charts in a single figure:

import matplotlib.pyplot as plt

# Data for the pie charts
labels = ['Python', 'Java', 'C++', 'Ruby']
sizes1 = [40, 30, 20, 10]
sizes2 = [25, 35, 25, 15]

# Create a figure with two subplots
fig, axes = plt.subplots(1, 2, figsize=(10, 5))

# First pie chart
axes[0].pie(sizes1, labels=labels, autopct='%1.1f%%')
axes[0].set_title('2024 Data', fontsize=14, color='green')

# Second pie chart
axes[1].pie(sizes2, labels=labels, autopct='%1.1f%%')
axes[1].set_title('2025 Data', fontsize=14, color='red')

# Show the plots
plt.tight_layout()
plt.show()

Explanation

1. The plt.subplots() function creates a figure with two subplots arranged side-by-side.
2. Each pie chart is plotted using the axes[i].pie() method, where i is the index of the subplot.
3. The set_title() method is used to add titles to individual subplots.

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Summary

In this tutorial, we covered:

• How to add a title to a pie chart using plt.title().
• Customization options for title appearance, such as font size, color, and alignment.
• Adding titles to multiple pie charts in a single figure.

With these techniques, you can create more informative and visually appealing pie charts in Python Matplotlib.