Allow passing emtpy list of ticks for FixedLocator

dstansby · dstansby · commit ba480545fa10 · 2020-06-28T11:36:57.000+01:00
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -1712,7 +1712,9 @@ def set_ticklabels(self, ticklabels, *, minor=False, **kwargs):
         locator = (self.get_minor_locator() if minor
                    else self.get_major_locator())
         if isinstance(locator, mticker.FixedLocator):
-            if len(locator.locs) != len(ticklabels):
+            # Passing [] as a list of ticklabels is often used as a way to
+            # remove all tick labels, so only error for > 0 ticklabels
+            if len(locator.locs) != len(ticklabels) and len(ticklabels) != 0:
                 raise ValueError(
                     "The number of FixedLocator locations"
                     f" ({len(locator.locs)}), usually from a call to"
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -4593,6 +4593,14 @@ def test_mismatched_ticklabels():
         ax.xaxis.set_ticklabels(['a', 'b', 'c'])
 
 
+def test_empty_ticks_fixed_loc():
+    # Smoke test that [] can be used to unset all tick labels
+    fig, ax = plt.subplots()
+    ax.bar([1, 2], [1, 2])
+    ax.set_xticks([1, 2])
+    ax.set_xticklabels([])
+
+
 @image_comparison(['retain_tick_visibility.png'])
 def test_retain_tick_visibility():
     fig, ax = plt.subplots()
