Merge pull request matplotlib#25712 from olinjohnson/fix-fill_between

Prevents axes limits from being resized by axes.fill_between

Author: ksunden

lib/matplotlib/axes/_axes.py

@@ -5431,7 +5431,12 @@ def get_interp_point(idx):
                             np.column_stack([ind[where], dep2[where]])])
         if ind_dir == "y":
             pts = pts[:, ::-1]
-        self.update_datalim(pts, updatex=True, updatey=True)
+
+        up_x = up_y = True
+        if "transform" in kwargs:
+            up_x, up_y = kwargs["transform"].contains_branch_seperately(self.transData)
+        self.update_datalim(pts, updatex=up_x, updatey=up_y)
+
         self.add_collection(collection, autolim=False)
         self._request_autoscale_view()
         return collection

lib/matplotlib/tests/test_axes.py

@@ -8572,3 +8572,19 @@ def test_ecdf_invalid():
         plt.ecdf([1, np.nan])
     with pytest.raises(ValueError):
         plt.ecdf(np.ma.array([1, 2], mask=[True, False]))
+
+
+def test_fill_between_axes_limits():
+    fig, ax = plt.subplots()
+    x = np.arange(0, 4 * np.pi, 0.01)
+    y = 0.1*np.sin(x)
+    threshold = 0.075
+    ax.plot(x, y, color='black')
+
+    original_lims = (ax.get_xlim(), ax.get_ylim())
+
+    ax.axhline(threshold, color='green', lw=2, alpha=0.7)
+    ax.fill_between(x, 0, 1, where=y > threshold,
+                    color='green', alpha=0.5, transform=ax.get_xaxis_transform())
+
+    assert (ax.get_xlim(), ax.get_ylim()) == original_lims