ERR: fixup exception reports for duplicate axis reindexing, related (GH7432)

Author: jreback

pandas/core/frame.py

@@ -2022,9 +2022,13 @@ def _sanitize_column(self, key, value):
                 # GH 4107
                 try:
                     value = value.reindex(self.index).values
-                except ValueError as e:
-                    raise e
-                except:
+                except Exception as e:
+
+                    # duplicate axis
+                    if not value.index.is_unique:
+                        raise e
+
+                    # other
                     raise TypeError('incompatible index of inserted column '
                                     'with frame index')
 

pandas/tests/test_frame.py

@@ -2467,6 +2467,13 @@ def test_constructor_with_embedded_frames(self):
 
     def test_insert_error_msmgs(self):
 
+        # GH 7432
+        df = DataFrame({'foo':['a', 'b', 'c'], 'bar':[1,2,3], 'baz':['d','e','f']}).set_index('foo')
+        s = DataFrame({'foo':['a', 'b', 'c', 'a'], 'fiz':['g','h','i','j']}).set_index('foo')
+        msg = 'cannot reindex from a duplicate axis'
+        with assertRaisesRegexp(ValueError, msg):
+            df['newcol'] = s
+
         # GH 4107, more descriptive error message
         df = DataFrame(np.random.randint(0,2,(4,4)),
                        columns=['a', 'b', 'c', 'd'])