Pie Charts in Matplotlib

Pie charts are used to display the proportions of parts of a whole. Each slice of the pie represents a category, with its size corresponding to its proportion.

Creating Pie Charts

The pie() function in Matplotlib is used to create pie charts.

Example: Basic Pie Chart

import matplotlib.pyplot as plt
 
# Data
labels = ['Python', 'Java', 'C++', 'JavaScript']
sizes = [215, 130, 245, 210]
 
# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%', startangle=90)
 
# Add title
plt.title("Programming Language Popularity")
 
# Display the plot
plt.show()

Customizing Pie Charts

Matplotlib provides several parameters to customize pie charts:

Parameter	Description	Example Value
`labels`	Names of the categories	`['A', 'B', 'C']`
`autopct`	Display format for percentage values	`'%1.1f%%'`
`startangle`	Starting angle of the chart	`90`
`colors`	Colors for each slice	`['red', 'blue']`
`explode`	Offset for slices (proportional values)	`[0.1, 0, 0]`

Example: Customized Pie Chart

# Data
labels = ['Apples', 'Bananas', 'Cherries', 'Dates']
sizes = [20, 30, 25, 25]
colors = ['gold', 'yellowgreen', 'lightcoral', 'lightskyblue']
explode = [0.1, 0, 0, 0]  # Explode the first slice
 
# Create customized pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%', startangle=140, colors=colors, explode=explode)
 
# Add title
plt.title("Fruit Distribution")
 
# Display the plot
plt.show()

Adding Legends and Annotations

Legends and annotations enhance the readability of pie charts.

Example: Pie Chart with Legend

# Data
labels = ['Rent', 'Groceries', 'Utilities', 'Entertainment']
sizes = [500, 300, 100, 100]
 
# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%', startangle=90)
plt.title("Monthly Expenses")
 
# Add legend
plt.legend(labels, title="Categories", loc="best")
 
# Display the plot
plt.show()

Practical Examples

Example 1: Survey Results

# Data
labels = ['Satisfied', 'Neutral', 'Dissatisfied']
sizes = [60, 25, 15]
colors = ['green', 'yellow', 'red']
 
# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%', startangle=90, colors=colors)
 
# Add title
plt.title("Customer Satisfaction Survey")
 
# Display the plot
plt.show()

# Data
labels = ['Company A', 'Company B', 'Company C', 'Company D']
sizes = [40, 30, 20, 10]
 
# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%', startangle=90, colors=['blue', 'orange', 'green', 'red'])
 
# Add title
plt.title("Market Share Distribution")
 
# Display the plot
plt.show()

Try It Yourself

Problem 1: Create a Pie Chart

Create a pie chart to represent the percentage distribution of your daily activities: sleeping, studying, exercising, and leisure.

Show Code

# Data
labels = ['Sleeping', 'Studying', 'Exercising', 'Leisure']
sizes = [8, 6, 2, 8]
 
# Create pie chart
plt.pie(sizes, labels=labels, autopct='%1.1f%%', startangle=90)
 
# Add title
plt.title("Daily Activity Distribution")
 
# Display the plot
plt.show()

Problem 2: Favorite Hobbies

Create a pie chart showing the distribution of survey responses for favorite hobbies.