Handle a mixture that includes pandas objects with non-default index

Fixes #1867

doc/releases/v0.9.1.txt

@@ -38,6 +38,8 @@ Bug fixes and adpatations
 
 - Fixed a bug when setting the rotation of x tick labels on a :class:`FacetGrid`.
 
+- Fixed a bug where values would be excluded from categorical plots when only one variable was a pandas ``Series`` with a non-default index.
+
 - Fixed a bug when using ``Series`` objects as arguments for ``x_partial`` or ``y_partial`` in :func:`regplot`.
 
 - Fixed a bug when passing a ``norm`` object and using color annotations in :func:`clustermap`.

seaborn/categorical.py

@@ -243,7 +243,11 @@ def _group_longform(self, vals, grouper, order):
         """Group a long-form variable by another with correct order."""
         # Ensure that the groupby will work
         if not isinstance(vals, pd.Series):
-            vals = pd.Series(vals)
+            if isinstance(grouper, pd.Series):
+                index = grouper.index
+            else:
+                index = None
+            vals = pd.Series(vals, index=index)
 
         # Group the val data
         grouped_vals = vals.groupby(grouper)

seaborn/tests/test_categorical.py

@@ -172,6 +172,12 @@ def test_single_long_direct_inputs(self):
         nt.assert_is(p.value_label, None)
         nt.assert_is(p.group_label, None)
 
+        # Test array and series with non-default index
+        x = pd.Series([1, 1, 1, 1], index=[0, 2, 4, 6])
+        y = np.array([1, 2, 3, 4])
+        p.establish_variables(x, y)
+        assert len(p.plot_data[0]) == 4
+
     def test_single_long_indirect_inputs(self):
 
         p = cat._CategoricalPlotter()