From dc2e073e429068c178ec6bccc971d5736fc4e560 Mon Sep 17 00:00:00 2001
From: Thor Whalen <1906276+thorwhalen@users.noreply.github.com>
Date: Mon, 7 Sep 2026 01:13:36 +0200
Subject: [PATCH] Use plt.get_cmap instead of removed-in-3.11 plt.cm.get_cmap

`scatter_and_color_according_to_y` resolved its colormap via
`plt.cm.get_cmap` (i.e. `matplotlib.cm.get_cmap`), which matplotlib
deprecated in 3.7 with `removal='3.11'`. Since the package pins no
matplotlib upper bound, the continuous-`y` branch of this public,
`__init__`-exported function would start raising `AttributeError` as
soon as users pick up 3.11.

Switch to `plt.get_cmap`, the non-deprecated spelling matplotlib's own
warning points at.

Verified equivalent under matplotlib 3.10 for every argument form the
call site can produce -- str, `Colormap`, and `None` all yield the same
colormap type and an identical 256-sample lookup table, and invalid
input still raises `ValueError` from both spellings. The change is
therefore observationally inert apart from dropping the warning.

Adds a regression test asserting the float-`y` path emits no
`MatplotlibDeprecationWarning`; it fails on the unmodified code with the
`get_cmap ... will be removed in 3.11` message and passes after.

Suite: 74 passed before, 75 passed after (the one new test). Two
pre-existing failures under the CI `--doctest-modules` invocation are
untouched and unrelated: `oplot/my.py` fails to import (`nympy` typo)
and the `plot_stats.smooth_scores` doctest fails; both reproduce
identically on the unmodified tree.

Claude-Session: https://claude.ai/code/session_01L1aQPB34n7PU7jmbztSjBe
---
 oplot/plot_data_set.py      |  2 +-
 tests/test_plot_data_set.py | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/oplot/plot_data_set.py b/oplot/plot_data_set.py
index 5e87911..62da3de 100644
--- a/oplot/plot_data_set.py
+++ b/oplot/plot_data_set.py
@@ -220,7 +220,7 @@ def scatter_and_color_according_to_y(
 
     elif isinstance(y[0], float):
         legend = False
-        cm = plt.cm.get_cmap(cmap_col)
+        cm = plt.get_cmap(cmap_col)
         colors = None
         col = 'continuous'
         no_tag = True
diff --git a/tests/test_plot_data_set.py b/tests/test_plot_data_set.py
index 800d671..0319a50 100644
--- a/tests/test_plot_data_set.py
+++ b/tests/test_plot_data_set.py
@@ -1,8 +1,11 @@
 """Tests for oplot.plot_data_set module"""
 
+import warnings
+
 import pytest
 import numpy as np
 import matplotlib.pyplot as plt
+from matplotlib import MatplotlibDeprecationWarning
 from matplotlib.axes import Axes
 
 from oplot.plot_data_set import (
@@ -112,6 +115,27 @@ def test_scatter_with_float_y(self):
         scatter_and_color_according_to_y(X, y, projection='2d', dim_reduct='PCA')
         plt.close('all')
 
+    def test_scatter_with_float_y_emits_no_deprecation_warning(self):
+        """Continuous-y colouring must not rely on deprecated matplotlib APIs.
+
+        ``matplotlib.cm.get_cmap`` (a.k.a. ``plt.cm.get_cmap``) is deprecated
+        since matplotlib 3.7 and slated for removal in 3.11, which would turn
+        the float-``y`` branch into an ``AttributeError``.
+        """
+        np.random.seed(42)
+        X = np.random.rand(50, 4)
+        y = np.random.rand(50)
+        with warnings.catch_warnings(record=True) as recorded:
+            warnings.simplefilter('always')
+            scatter_and_color_according_to_y(X, y, projection='2d', dim_reduct='PCA')
+        plt.close('all')
+        deprecations = [
+            str(w.message)
+            for w in recorded
+            if issubclass(w.category, MatplotlibDeprecationWarning)
+        ]
+        assert not deprecations, f'deprecated matplotlib API used: {deprecations}'
+
     def test_scatter_1d(self):
         """Test 1D scatter plot"""
         np.random.seed(42)