BUG: Bug in Panel.apply with a multi-index as an axis (GH7469)

Author: jreback

doc/source/v0.14.1.txt

@@ -163,7 +163,7 @@ Bug Fixes
 
 
 
-
+- Bug in ``Panel.apply`` with a multi-index as an axis (:issue:`7469`)
 
 
 - Bug in ``DatetimeIndex.insert`` doesn't preserve ``name`` and ``tz`` (:issue:`7299`)

pandas/tests/test_panel.py

@@ -1180,6 +1180,16 @@ def test_apply_slabs(self):
         expected = Panel(dict([ (ax,f(self.panel.loc[:,ax])) for ax in self.panel.major_axis ]))
         assert_panel_equal(result,expected)
 
+        # with multi-indexes
+        # GH7469
+        index = MultiIndex.from_tuples([('one', 'a'), ('one', 'b'), ('two', 'a'), ('two', 'b')])
+        dfa = DataFrame(np.array(np.arange(12, dtype='int64')).reshape(4,3), columns=list("ABC"), index=index)
+        dfb = DataFrame(np.array(np.arange(10, 22, dtype='int64')).reshape(4,3), columns=list("ABC"), index=index)
+        p = Panel({'f':dfa, 'g':dfb})
+        result = p.apply(lambda x: x.sum(), axis=0)
+        expected = p.sum(0)
+        assert_frame_equal(result,expected)
+
     def test_reindex(self):
         ref = self.panel['ItemB']
 

pandas/tools/util.py

@@ -3,6 +3,7 @@
 from pandas.core.index import Index
 import numpy as np
 from pandas import algos
+from pandas.core import common as com
 
 
 def match(needles, haystack):
@@ -32,7 +33,7 @@ def cartesian_product(X):
 
     b = cumprodX[-1] / cumprodX
 
-    return [np.tile(np.repeat(np.asarray(x), b[i]),
+    return [np.tile(np.repeat(np.asarray(com._values_from_object(x)), b[i]),
                     np.product(a[i]))
                for i, x in enumerate(X)]