Matplotlib Pie Charts

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Creating pie charts in Matplotlib is straightforward. You can use the plt.pie() function to generate pie charts. Here’s a comprehensive guide on how to create and customize pie charts in Matplotlib.

Basic Pie Chart

To create a basic pie chart, you need to provide a list of values that represent the sizes of the pie slices.

        import matplotlib.pyplot as plt

        # Data
        sizes = [15, 30, 45, 10]
        
        # Create a pie chart
        plt.pie(sizes)
        plt.show()
      

Adding Labels

You can add labels to each slice of the pie chart by using the labels parameter.

        # Data
        sizes = [15, 30, 45, 10]
        labels = ['A', 'B', 'C', 'D']
        
        # Create a pie chart with labels
        plt.pie(sizes, labels=labels)
        plt.show()
      

Customizing Colors

You can customize the colors of the pie chart slices using the colors parameter.

        # Data
        sizes = [15, 30, 45, 10]
        labels = ['A', 'B', 'C', 'D']
        colors = ['gold', 'yellowgreen', 'lightcoral', 'lightskyblue']
        
        # Create a pie chart with custom colors
        plt.pie(sizes, labels=labels, colors=colors)
        plt.show()
      

Adding a Legend

Adding a legend to the pie chart can make it more informative.

        # Data
        sizes = [15, 30, 45, 10]
        labels = ['A', 'B', 'C', 'D']
        colors = ['gold', 'yellowgreen', 'lightcoral', 'lightskyblue']
        
        # Create a pie chart with a legend
        plt.pie(sizes, labels=labels, colors=colors)
        plt.legend(labels, loc='best')
        plt.show()
      

Exploding Slices

You can "explode" one or more slices away from the center to highlight them using the explode parameter.

        # Data
        sizes = [15, 30, 45, 10]
        labels = ['A', 'B', 'C', 'D']
        colors = ['gold', 'yellowgreen', 'lightcoral', 'lightskyblue']
        explode = (0, 0.1, 0, 0)  # Only "explode" the 2nd slice (i.e. 'B')
        
        # Create a pie chart with exploded slice
        plt.pie(sizes, labels=labels, colors=colors, explode=explode)
        plt.show()
      

Adding Percentages

You can add percentages to the slices using the autopct parameter.

        # Data
        sizes = [15, 30, 45, 10]
        labels = ['A', 'B', 'C', 'D']
        colors = ['gold', 'yellowgreen', 'lightcoral', 'lightskyblue']
        
        # Create a pie chart with percentages
        plt.pie(sizes, labels=labels, colors=colors, autopct='%1.1f%%')
        plt.show()
      

Full Example

Here’s a more comprehensive example that incorporates several of the customizations discussed:

        import matplotlib.pyplot as plt

        # Data
        sizes = [15, 30, 45, 10]
        labels = ['A', 'B', 'C', 'D']
        colors = ['gold', 'yellowgreen', 'lightcoral', 'lightskyblue']
        explode = (0, 0.1, 0, 0)  # Only "explode" the 2nd slice (i.e. 'B')
        
        # Create a pie chart
        plt.pie(sizes, explode=explode, labels=labels, colors=colors, autopct='%1.1f%%',
                shadow=True, startangle=140)
        
        # Equal aspect ratio ensures that pie is drawn as a circle.
        plt.axis('equal')
        
        # Add legend
        plt.legend(labels, loc='best')
        
        # Show plot
        plt.title('Custom Pie Chart')
        plt.show()
      

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