[FIXED] Adding Comma to Bar Labels in MatplotLib

Issue

I have been using the ax.bar_label method to add data values to the bar graphs. The numbers are huge such as 143858918. How can I add commas to the data values using the ax.bar_label method? I do know how to add commas using the annotate method but if it is possible using bar_label, I am not sure. Is it possible using the fmt keyword argument that is available?

Solution

• fmt still uses the old % operator (as of 3.5.1), which doesn't support comma separators (as far as I know).
• Instead, use the labels param with f-strings.

Get the heights of the container patches and format them with {:,} to get comma separators:

container = ax.containers[0]
ax.bar_label(container, labels=[f'{p.get_height():,}' for p in container])

Or for grouped bar charts, iterate all the containers:

for container in ax.containers:
    ax.bar_label(container, labels=[f'{p.get_height():,}' for p in container])

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Toy example:

x = np.random.default_rng(123).integers(10_000_000, size=5)
fig, ax = plt.subplots()
ax.bar(range(len(x)), x)

container = ax.containers[0]
ax.bar_label(container, labels=[f'{p.get_height():,}' for p in container])

Answered By - tdy