Fix bar_label for bars with nan values

Author: timhoffm

lib/matplotlib/axes/_axes.py

@@ -2625,14 +2625,15 @@ def sign(x):
             if label_type == "center":
                 ha, va = "center", "center"
             elif label_type == "edge":
-                if orientation == "vertical" and dat >= 0:
-                    ha, va = "center", "bottom"
-                elif orientation == "vertical" and dat < 0:
-                    ha, va = "center", "top"
-                elif orientation == "horizontal" and dat >= 0:
-                    ha, va = "left", "center"
-                elif orientation == "horizontal" and dat < 0:
-                    ha, va = "right", "center"
+                if orientation == "vertical":
+                    ha = 'center'
+                    va = 'top' if dat < 0 else 'bottom'  # also handles NaN
+                elif orientation == "horizontal":
+                    ha = 'right' if dat < 0 else 'left'  # also handles NaN
+                    va = 'center'
+
+            if np.isnan(dat):
+                lbl = ''
 
             annotation = self.annotate(fmt % value if lbl is None else lbl,
                                        xy, xytext, textcoords="offset points",

lib/matplotlib/tests/test_axes.py

@@ -7027,6 +7027,15 @@ def test_bar_label_labels():
     assert labels[1].get_text() == 'B'
 
 
+def test_bar_label_nan_ydata():
+    ax = plt.gca()
+    bars = ax.bar([2, 3], [np.nan, 1])
+    labels = ax.bar_label(bars)
+    assert [l.get_text() for l in labels] == ['', '1']
+    assert labels[0].xy == (2, 0)
+    assert labels[0].get_va() == 'bottom'
+
+
 def test_patch_bounds():  # PR 19078
     fig, ax = plt.subplots()
     ax.add_patch(mpatches.Wedge((0, -1), 1.05, 60, 120, 0.1))