ENH: Add support for per-label padding in bar_label #29696

brifore13 · Mar 2, 2025

PR summary

PR checklist

[X ] "closes [ENH]: Allow list of padding values for bar_label #29647 " is in the body of the PR description to [(https://github.com/[ENH]: Allow list of padding values for bar_label #29647)]
[ X] new and changed code is tested
[X ] Plotting related features are demonstrated in an example
New Features and API Changes are noted with a directive and release note
[ X] Documentation complies with general and docstring guidelines

Implement support for array-like padding in bar_label. This allows users to specify different padding values for individual labels by passing an array-like object to the padding parameter. Updated the docstring to reflect acceptance of float or array-like of correct length. Ex: ax.bar_label(bars, padding=[3, 3, 3, 15])

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rcomer

Please also add unit tests to verify that the new behaviour does what you intend.

rcomer · Mar 2, 2025

lib/matplotlib/axes/_axes.py

-        for bar, err, dat, lbl in itertools.zip_longest(
-                bars, errs, datavalues, labels
+        try:
+            if not isinstance(padding, (str, bytes)) and np.iterable(padding):


I do not think it is necessary to check for string or bytes object here. Currently we assume the user correctly passed a float, so I think in future we can assume they correctly passed a float or iterable.

Thanks @rcomer, currently making the corrections and will add unit tests. This is my first PR request, so thank you for your help and patience.

Thanks @brifore13, if you need any help, feel free to ask questions here. Or you may prefer to ask them in our incubator gitter room.

rcomer · Mar 2, 2025

lib/matplotlib/axes/_axes.py

+                if len(padding_array) != len(bars):
+                    raise ValueError(
+                        f"padding must be of length {len(bars)} when passed as a sequence")
+                padding_list = list(padding_array)


The array will work fine in zip_longest, so we do not need to convert this to a list.

rcomer · Mar 2, 2025

lib/matplotlib/axes/_axes.py

+            else:
+                # single value, apply to all labels
+                padding_list = [padding] * len(bars)
+        except (TypeError, ValueError):


This will catch the ValueError you added for the wrong length iterable. I do not think you meant to do that.

rcomer · Mar 2, 2025

lib/matplotlib/axes/_axes.py

+                # single value, apply to all labels
+                padding_list = [padding] * len(bars)
+        except (TypeError, ValueError):
+            # not iterable or wrong length, use scalar padding


you already handled the "not iterable" case with the else on line 2948.

rcomer · Mar 2, 2025

The type hint will also need updating

matplotlib/lib/matplotlib/axes/_axes.pyi

Line 271 in 03b74ea

padding: float = ...,

story645 · Mar 4, 2025

try installing the pre-commit hooks to help spot and fix the pre-commit errors:

https://matplotlib.org/devdocs/devel/development_setup.html#install-pre-commit-hooks

Added unit testing for float and array-like processing. Modified logic based on requested changes. Updated type hint.

rcomer

Thanks @brifore13 I think this is looking in good shape now. I just have some minor comments on the change and you will also need to run boilerplate.py so that pyplot.bar_label gets updated too.

rcomer · Mar 6, 2025

lib/matplotlib/axes/_axes.py

-                bars, errs, datavalues, labels
+        if np.iterable(padding):
+            # if padding iterable, check length
+            padding_array = np.asarray(padding)


Suggested change

padding_array = np.asarray(padding)

padding = np.asarray(padding)

I suggest to just call this padding as it may end up an array or list and we don't mind which. It means we replace the original padding but that is OK since we were not going to need the original again.

rcomer · Mar 6, 2025

lib/matplotlib/tests/test_axes.py

+    ax = plt.gca()
+    rects = ax.bar(xs, heights)


Suggested change

ax = plt.gca()

rects = ax.bar(xs, heights)

For efficiency, we can remove these lines and just reuse the original rects.

1. ran boilerplate.py 2. padding_array to padding 3. removed second rects in unit testing

timhoffm

This should get a What's New entry. See https://matplotlib.org/devdocs/users/next_whats_new/README.html

lib/matplotlib/axes/_axes.py

doc/users/next_whats_new/bar_label_padding_update.rst

lib/matplotlib/axes/_axes.py

timhoffm · Mar 18, 2025

Thanks @brifore13, and congratulations on your first contribution to Matplotlib! 🎉 We'd welcome to see you back!

github-actions bot reviewed Mar 2, 2025

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rcomer requested changes Mar 2, 2025

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Add unit tests and modified logic for bar_label padding

5bfa212

Added unit testing for float and array-like processing. Modified logic based on requested changes. Updated type hint.

melissawm added this to First Time Contributors Mar 5, 2025

melissawm moved this to Needs review in First Time Contributors Mar 5, 2025

rcomer reviewed Mar 6, 2025

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rcomer added the New feature label Mar 7, 2025

rcomer added this to the v3.11.0 milestone Mar 7, 2025

Update pyplot, completed requested changes

f8985e2

1. ran boilerplate.py 2. padding_array to padding 3. removed second rects in unit testing

github-actions bot added the topic: pyplot API label Mar 10, 2025

rcomer approved these changes Mar 10, 2025

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timhoffm reviewed Mar 10, 2025

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lib/matplotlib/axes/_axes.py Show resolved Hide resolved

Added a whats new entry

8fc5578

timhoffm reviewed Mar 18, 2025

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doc/users/next_whats_new/bar_label_padding_update.rst Outdated Show resolved Hide resolved

Versionadded and more concise wording of whats new

fde2fa2

timhoffm approved these changes Mar 18, 2025

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timhoffm reviewed Mar 18, 2025

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lib/matplotlib/axes/_axes.py Outdated Show resolved Hide resolved

Fix whitespace

7f6fffe

timhoffm merged commit f730235 into matplotlib:main Mar 18, 2025
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github-project-automation bot moved this from Needs review to Waiting for author in First Time Contributors Mar 18, 2025

QuLogic moved this from Waiting for author to Merged in First Time Contributors Mar 18, 2025

	padding_array = np.asarray(padding)
	padding = np.asarray(padding)

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ENH: Add support for per-label padding in bar_label #29696

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brifore13 commented Mar 2, 2025

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rcomer commented Mar 2, 2025

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timhoffm commented Mar 18, 2025

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