How to Add Value Labels to a Matplotlib Bar Chart?

Adding Value Labels to a Bar Chart

To add value labels to the bars of a bar chart, you can utilize either the 'text' or 'annotate' methods provided by matplotlib. Each method offers distinct advantages and usage scenarios.

Using the 'text' Method

The 'text' method allows you to place text directly on the plot at specific coordinates. For a bar chart, you can use the following approach:

• Retrieve the list of bars from the plot using the 'ax.patches' member.
• Construct a list of labels for each bar.
• Iterate through the bars and labels, using the 'ax.text' method to add a label to each bar. The text should be positioned based on the bar's coordinates.

Using the 'annotate' Method

The 'annotate' method provides more flexibility in annotating plots, including adding arrowed lines and labels. To annotate a bar chart with value labels, you can utilize the following steps:

• Get the coordinates of each bar's midpoint.
• For each midpoint, call 'ax.annotate' to add a text annotation.
• Position the text slightly above or within the bar, depending on your preference.

Example Code

The following code demonstrates how to add value labels to a bar chart using the 'text' method:

import matplotlib.pyplot as plt

# Data and plot setup
data = [6, 16, 75, 160, 244, 260, 145, 73, 16, 4, 1]
plt.bar(range(len(data)), data)

# Add value labels
for bar, value in zip(plt.gca().patches, data):
    height = bar.get_height()
    plt.text(bar.get_x() + bar.get_width() / 2, height, f'{value}', ha='center', va='bottom')

plt.show()

Running this code produces a bar chart with value labels centered within each bar. Adjust the positioning parameters in 'plt.text' as needed to achieve the desired location for the labels.

The above is the detailed content of How to Add Value Labels to a Matplotlib Bar Chart?. For more information, please follow other related articles on the PHP Chinese website!