How to annotate a grouped bar chart in Matplotlib with multiple values for each bar?-Python Tutorial-php.cn

How to annotate a grouped bar chart in Matplotlib with multiple values for each bar?

Mary-Kate Olsen

Release： 2024-10-27 10:24:30

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How to annotate a grouped bar chart in Matplotlib with multiple values for each bar?

Multiple Annotations for Grouped Bar Chart

Problem:
When attempting to create a grouped bar chart using Matplotlib, the output appears incorrect.

Code Example:

<code class="python">import matplotlib.pyplot as plt

# sample data
labels = ['Label 1', 'Label 2', 'Label 3']
data1 = [5, 10, 15]
data2 = [15, 10, 5]

# create the bar chart
plt.bar(labels, data1, 0.4, label='Data Set 1')
plt.bar(labels, data2, 0.4, label='Data Set 2', bottom=data1)

# attempt to annotate each bar
for i in range(3):
    plt.annotate(data1[i], (labels[i], data1[i]), xytext=(-5, 5), textcoords='offset points')
    plt.annotate(data2[i], (labels[i], data2[i]+data1[i]), xytext=(-5, 5), textcoords='offset points')

plt.legend()
plt.show()</code>

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Expected Output:

Each bar should be annotated with its respective value.

Resolution:

Method 1: Using bar_label

<code class="python">import matplotlib.pyplot as plt

plt.bar(labels, data1, 0.4, label='Data Set 1')
plt.bar(labels, data2, 0.4, label='Data Set 2', bottom=data1)

for i in range(3):
    plt.bar_label(plt.gca().containers[i], labels=(data1[i], data2[i]), fmt='%.1f', padding=10)

plt.legend()
plt.show()</code>

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Method 2: Using annotate

<code class="python">import matplotlib.pyplot as plt

plt.bar(labels, data1, 0.4, label='Data Set 1')
plt.bar(labels, data2, 0.4, label='Data Set 2', bottom=data1)

for i in range(3):
    height1 = data1[i]
    height2 = data2[i]

    # annotate for data set 1
    plt.annotate(str(height1), (labels[i], height1), xytext=(0, 5), textcoords='offset points')

    # annotate for data set 2
    plt.annotate(str(height2), (labels[i], height1 + height2), xytext=(0, 5), textcoords='offset points')

plt.legend()
plt.show()
````
</code>

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