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[MNT]: handle new deprecation from numpy (casting single-element arrays to scalar) #25744

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neutrinoceros opened this issue Apr 21, 2023 · 3 comments
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[MNT]: handle new deprecation from numpy (casting single-element arrays to scalar) #25744

neutrinoceros opened this issue Apr 21, 2023 · 3 comments
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Maintenance status: downstream fix required

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@neutrinoceros
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Summary

For context, see numpy/numpy#10615

One way matplotlib currently hits the new deprecation warning (there might be others) can be reproduced as

# t.py
import matplotlib.pyplot as plt
import numpy as np

fig, ax = plt.subplots()
ax.set_ylim(np.array([-1]), 1)
$ python -Werror t.py

Traceback (most recent call last):
  File "/Users/robcleme/dev/matplotlib/t.py", line 6, in <module>
    ax.set_ylim(np.array([-1]), 1)
  File "/Users/robcleme/dev/matplotlib/lib/matplotlib/axes/_base.py", line 3873, in set_ylim
    return self.yaxis._set_lim(bottom, top, emit=emit, auto=auto)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/robcleme/dev/matplotlib/lib/matplotlib/axis.py", line 1214, in _set_lim
    v0, v1 = self.get_major_locator().nonsingular(v0, v1)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/robcleme/dev/matplotlib/lib/matplotlib/ticker.py", line 1644, in nonsingular
    return mtransforms.nonsingular(v0, v1, expander=.05)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/robcleme/dev/matplotlib/lib/matplotlib/transforms.py", line 2844, in nonsingular
    vmin, vmax = map(float, [vmin, vmax])
    ^^^^^^^^^^
DeprecationWarning: Conversion of an array with ndim > 0 to a scalar is deprecated, and will error in future. Ensure you extract a single element from your array before performing this operation. (Deprecated NumPy 1.25.)

Proposed fix

The following patch resolves the one issue for which I included a reproducer

diff --git a/lib/matplotlib/transforms.py b/lib/matplotlib/transforms.py
index 03c8a9f97a..aa345fb295 100644
--- a/lib/matplotlib/transforms.py
+++ b/lib/matplotlib/transforms.py
@@ -2841,7 +2841,7 @@ def nonsingular(vmin, vmax, expander=0.001, tiny=1e-15, increasing=True):

     # Expand vmin, vmax to float: if they were integer types, they can wrap
     # around in abs (abs(np.int8(-128)) == -128) and vmax - vmin can overflow.
-    vmin, vmax = map(float, [vmin, vmax])
+    vmin, vmax = map(lambda x: float(np.asarray(x).item()), [vmin, vmax])

     maxabsvalue = max(abs(vmin), abs(vmax))
     if maxabsvalue < (1e6 / tiny) * np.finfo(float).tiny:

I will open a PR with this patch, but careful inspection is needed to make sure the rest of the code base is safe.
@neutrinoceros neutrinoceros mentioned this issue Apr 21, 2023
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@jklymak
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jklymak commented Apr 21, 2023

Are we testing on numpy 1.25?

@tacaswell
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our nightly cron job should be catching that and I am hitting it in an ad-hoc way on my local machine.

@tacaswell
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See #25745 (comment)

I am going to close this as no-action as the user passing us (1,) shaped arrays for scalars is a bug in the caller code that happened to work due to a (now deprecated) quirk of the numpy implementation.

@tacaswell tacaswell closed this as not planned Won't fix, can't repro, duplicate, stale Apr 21, 2023
@mwaskom mwaskom mentioned this issue Aug 25, 2023
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@tacaswell @QuLogic @jklymak @neutrinoceros