consolidate code and split up tests for set_levels

Author: leej3

pandas/core/indexes/multi.py

@@ -163,7 +163,12 @@ def _set_levels(self, levels, level=None, copy=False, validate=True,
         # externally not allowed to set levels. User beware if you change
         # _levels directly
         if validate and len(levels) == 0:
-            raise ValueError('Must set non-zero number of levels.')
+            if is_list_like(level):
+                raise ValueError('Must set non-zero number of levels with '
+                                 'current value of level')
+            else:
+                assert(False)
+                raise ValueError('Must set non-zero number of levels.')
         if validate and level is None and len(levels) != self.nlevels:
             raise ValueError('Length of levels must match number of levels.')
         if validate and level is not None and len(levels) != len(level):
@@ -235,26 +240,8 @@ def set_levels(self, levels, level=None, inplace=False,
                    labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
                    names=[u'foo', u'bar'])
         """
-
-        level_list_like = level is None or is_list_like(level)
-        levels_list_like = (is_list_like(levels) and
-                            all(is_list_like(x) for x in levels) and
-                            levels != [] )
-
-        if level_list_like:
-            # level is a list-like object of scalars
-            levels_error = ("`levels` and `level` are incompatible. "
-                            "When `level` is list-like, `levels` must be a "
-                            "list-like object containing list-like objects")
-            if not levels_list_like:
-                raise TypeError(levels_error)
-        elif not level_list_like:
-            # level is a scalar
-            levels_error = ("`levels` and `level` are incompatible. "
-                            "When `level` is a scalar, `levels` must be a "
-                            " list-like object of scalars.")
-            if levels_list_like:
-                raise TypeError(levels_error)
+        if not (level is None or is_list_like(level)):
+            # level is a scalar, not list-like
             level = [level]
             levels = [levels]
 

pandas/tests/indexing/test_multiindex.py

@@ -428,7 +428,7 @@ def test_xs_multiindex(self):
         expected.columns = expected.columns.droplevel('lvl1')
         tm.assert_frame_equal(result, expected)
 
-    def test_set_level_checkall(self):
+    def test_set_level_with_level_as_default(self):
 
         idx = MultiIndex.from_tuples([(1, u'one'), (1, u'two'),
                                      (2, u'one'), (2, u'two')],
@@ -439,32 +439,64 @@ def test_set_level_checkall(self):
                               names=[u'foo', u'bar'])
         tm.assert_index_equal(result, expected)
 
+    def test_set_level_with_level_as_int(self):
+
+        idx = MultiIndex.from_tuples([(1, u'one'), (1, u'two'),
+                                     (2, u'one'), (2, u'two')],
+                                     names=['foo', 'bar'])
         result = idx.set_levels(['a', 'b'], level=0)
         expected = MultiIndex(levels=[[u'a', u'b'], [u'one', u'two']],
                               labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
                               names=[u'foo', u'bar'])
         tm.assert_index_equal(result, expected)
 
+    def test_set_level_with_level_as_string(self):
+
+        idx = MultiIndex.from_tuples([(1, u'one'), (1, u'two'),
+                                     (2, u'one'), (2, u'two')],
+                                     names=['foo', 'bar'])
         result = idx.set_levels(['a', 'b'], level='bar')
         expected = MultiIndex(levels=[[1, 2], [u'a', u'b']],
                               labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
                               names=[u'foo', u'bar'])
         tm.assert_index_equal(result, expected)
 
+    def test_set_level_with_level_as_list(self):
+
+        idx = MultiIndex.from_tuples([(1, u'one'), (1, u'two'),
+                                     (2, u'one'), (2, u'two')],
+                                     names=['foo', 'bar'])
         result = idx.set_levels([['a', 'b'], [1, 2]], level=[0, 1])
         expected = MultiIndex(levels=[[u'a', u'b'], [1, 2]],
                               labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
                               names=[u'foo', u'bar'])
         tm.assert_index_equal(result, expected)
 
+    def test_set_levels_with_empty_list_treated_as_scalar(self):
+
+        idx = MultiIndex(levels=[['a', 'b'], [1, 2]], labels=[[], []])
+        result = idx.set_levels([], level=0)
+        expected = MultiIndex(levels=[[], [1, 2]], labels=[[], []])
+        tm.assert_index_equal(result, expected)
+
+    # def test_set_levels_with_empty_list_treated_as_list_like(self):
+    #     # i dont' think this should pass
+    #     idx = MultiIndex(levels=[['a', 'b'], [1, 2]], labels=[[], []])
+    #     result = idx.set_levels([], level=[0,1])
+    #     expected = MultiIndex(levels=[[], []], labels=[[], []])
+    #     tm.assert_index_equal(result, expected)
+
+    def test_set_level_assigning_empty_level(self):
+
+        # GH16147
         # setting empty levels are allowed
         idx = MultiIndex(levels=[['L1'], ['L2']], labels=[[], []],
                          names=['a', 'b'])
         result = idx.set_levels([], level='a')
         expected = MultiIndex(levels=[[], ['L2']], labels=[[], []],
                               names=['a', 'b'])
         tm.assert_index_equal(result, expected)
-
+        
         idx = MultiIndex(levels=[['L1'], ['L2']], labels=[[], []],
                          names=['a', 'b'])
         result = idx.set_levels([[], []], level=['a', 'b'])