How to add a legend to a Matplotlib pie chart?

A legend in a Matplotlib pie chart helps identify different sections by mapping colors to category names. You can add a legend using the legend() method with the patches returned by pie().

Basic Pie Chart with Legend

Create a simple pie chart and add a legend using patches ?

import matplotlib.pyplot as plt

# Data for the pie chart
labels = ['Walk', 'Talk', 'Sleep', 'Work']
sizes = [23, 45, 12, 20]
colors = ['red', 'blue', 'green', 'yellow']

# Create pie chart and get patches
patches, texts = plt.pie(sizes, colors=colors, shadow=True, startangle=90)

# Add legend
plt.legend(patches, labels, loc="best")

# Make the pie chart circular
plt.axis('equal')

plt.title('Daily Activities')
plt.show()

Legend with Custom Position

You can position the legend at specific locations using the loc parameter ?

import matplotlib.pyplot as plt

labels = ['Python', 'Java', 'JavaScript', 'C++']
sizes = [35, 25, 25, 15]
colors = ['#ff9999', '#66b3ff', '#99ff99', '#ffcc99']

patches, texts = plt.pie(sizes, colors=colors, autopct='%1.1f%%', startangle=140)

# Legend positioned on the right
plt.legend(patches, labels, loc='center left', bbox_to_anchor=(1, 0.5))

plt.axis('equal')
plt.title('Programming Languages Usage')
plt.tight_layout()
plt.show()

Legend Options

Key Points

• Use patches, texts = plt.pie() to get legend handles
• The legend() method takes patches and labels as arguments
• Use loc parameter to control legend position
• Add bbox_to_anchor for precise positioning outside the plot area
• Use tight_layout() to prevent legend cutoff

Conclusion

Adding a legend to pie charts improves readability by clearly labeling each section. Use the legend() method with patches from pie() and customize the position as needed.