Merge pull request matplotlib#23698 from stefmolin/bar-label-center

Fix bug in `Axes.bar_label(label_type='center')` for non-linear scales.

Author: greglucas

lib/matplotlib/axes/_axes.py

@@ -2715,7 +2715,13 @@ def sign(x):
                 value = extrema
 
             if label_type == "center":
-                xy = xc, yc
+                xy = (0.5, 0.5)
+                kwargs["xycoords"] = (
+                    lambda r, b=bar:
+                        mtransforms.Bbox.intersection(
+                            b.get_window_extent(r), b.get_clip_box()
+                        )
+                )
             else:  # edge
                 if orientation == "vertical":
                     xy = xc, endpt

lib/matplotlib/tests/baseline_images/test_axes/test_centered_bar_label_nonlinear.svg

@@ -7792,14 +7792,24 @@ def test_bar_label_location_center():
     ys, widths = [1, 2], [3, -4]
     rects = ax.barh(ys, widths)
     labels = ax.bar_label(rects, label_type='center')
-    assert labels[0].xy == (widths[0] / 2, ys[0])
+    assert labels[0].xy == (0.5, 0.5)
     assert labels[0].get_ha() == 'center'
     assert labels[0].get_va() == 'center'
-    assert labels[1].xy == (widths[1] / 2, ys[1])
+    assert labels[1].xy == (0.5, 0.5)
     assert labels[1].get_ha() == 'center'
     assert labels[1].get_va() == 'center'
 
 
+@image_comparison(['test_centered_bar_label_nonlinear.svg'])
+def test_centered_bar_label_nonlinear():
+    _, ax = plt.subplots()
+    bar_container = ax.barh(['c', 'b', 'a'], [1_000, 5_000, 7_000])
+    ax.set_xscale('log')
+    ax.set_xlim(1, None)
+    ax.bar_label(bar_container, label_type='center')
+    ax.set_axis_off()
+
+
 def test_bar_label_location_errorbars():
     ax = plt.gca()
     xs, heights = [1, 2], [3, -4]