Only the first row of annotations displayed on seaborn heatmap

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As it’s usually advised, I have managed to reduce my problem to a minimal reproducible example:

import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt

matrix = np.array([[0.1234, 1.4567, 0.7890, 0.1234],
                   [0.9876, 0, 0.5432, 0.6789],
                   [0.1111, 0.2222, 0, 0.3333],
                   [0.4444, 0.5555, 0.6666, 0]])
sns.heatmap(matrix, annot=True)
plt.show()

Vaguely based on Seaborn official documentation.

Unfortunately, unlike what would be expected (all numbers visible), I get only the numbers in the top row visible:

enter image description here

As there is not really much room for error in this one, I’m out of ideas and google/SO doesn’t seem to have this question asked before. Is this a bug?

I am running:

Seaborn 0.12.2
Matplotlib 3.8.0
PyCharm 2023.1.4
Windows 10

  • Using seaborn version 0.12.2 the plot has all the annotations. What version are you on?

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  • I ran and got the excepted output on the 0.12.2 version

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  • Updated the post with my environment

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  • My environment (on Windows 10) is running Matplotlib 3.7.1. The PyCharm version shouldn’t affect the results. Maybe it’s a bug related to a new version of Matplotlib?

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  • 2

    This is a result of a change in matplotlib: github.com/mwaskom/seaborn/issues/3478

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Thanks to a comment by @mwaskom, it seems like it’s a Matplotlib issue with a documented solution:

Looks like problem goes away if I downgrade MATPLOTLIB to version 3.7.3.

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