set_ticks([single_tick]) should also expand view limits.

anntzer · anntzer · commit 5ab9436ccf7a · 2021-10-22T11:56:54.000+02:00
Previously, the single-tick case would not perform expansion. (Curiously, the `len > 1` check was added in 0b48047 to fix inversion handling, and then cb5cab4 tried another fix apparently for the same problem (by making set_view_limits maintain preexisting inversions).)
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -1801,13 +1801,10 @@ def _set_tick_locations(self, ticks, *, minor=False):
                 break
         else:
             shared = [self]
-        for axis in shared:
-            if len(ticks) > 1:
-                xleft, xright = axis.get_view_interval()
-                if xright > xleft:
-                    axis.set_view_interval(min(ticks), max(ticks))
-                else:
-                    axis.set_view_interval(max(ticks), min(ticks))
+        if len(ticks):
+            for axis in shared:
+                # set_view_interval maintains any preexisting inversion.
+                axis.set_view_interval(min(ticks), max(ticks))
         self.axes.stale = True
         if minor:
             self.set_minor_locator(mticker.FixedLocator(ticks))
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -6808,6 +6808,8 @@ def test_set_ticks_inverted():
     ax.invert_xaxis()
     ax.set_xticks([.3, .7])
     assert ax.get_xlim() == (1, 0)
+    ax.set_xticks([-1])
+    assert ax.get_xlim() == (1, -1)
 
 
 def test_aspect_nonlinear_adjustable_box():
