BUG: fixed issue with drop on a non-unique index with Series (GH5248)

Author: jreback

doc/source/release.rst

@@ -621,6 +621,7 @@ Bug Fixes
     non-business date. (:issue:`5203`)
   - Fixed bug in Excel writers where frames with duplicate column names weren't
     written correctly. (:issue:`5235`)
+  - Fixed issue with ``drop`` and a non-unique index on Series (:issue:`5248`)
 
 pandas 0.12.0
 -------------

pandas/core/generic.py

@@ -1103,6 +1103,8 @@ def drop(self, labels, axis=0, level=None):
         """
         axis_name = self._get_axis_name(axis)
         axis, axis_ = self._get_axis(axis), axis
+        if not is_list_like(labels):
+            labels = [ labels ]
 
         if axis.is_unique:
             if level is not None:

pandas/core/indexing.py

@@ -581,9 +581,11 @@ def _multi_take_opportunity(self, tup):
             return False
 
         # just too complicated
-        for ax in self.obj._data.axes:
+        for indexer, ax in zip(tup,self.obj._data.axes):
             if isinstance(ax, MultiIndex):
                 return False
+            elif com._is_bool_indexer(indexer):
+                return False
 
         return True
 

pandas/tests/test_frame.py

@@ -3175,9 +3175,11 @@ def check(result, expected=None):
 
         # drop
         df = DataFrame([[1,5,7.],[1,5,7.],[1,5,7.]],columns=['bar','a','a'])
-        df = df.drop(['a'],axis=1)
+        result = df.drop(['a'],axis=1)
         expected = DataFrame([[1],[1],[1]],columns=['bar'])
-        check(df,expected)
+        check(result,expected)
+        result = df.drop('a',axis=1)
+        check(result,expected)
 
         # describe
         df = DataFrame([[1,1,1],[2,2,2],[3,3,3]],columns=['bar','a','a'],dtype='float64')

pandas/tests/test_series.py

@@ -1415,6 +1415,31 @@ def test_mask(self):
         rs = s.where(cond, np.nan)
         assert_series_equal(rs, s.mask(~cond))
 
+    def test_drop(self):
+
+        # unique
+        s = Series([1,2],index=['one','two'])
+        expected = Series([1],index=['one'])
+        result = s.drop(['two'])
+        assert_series_equal(result,expected)
+        result = s.drop('two')
+        assert_series_equal(result,expected)
+
+        # non-unique
+        # GH 5248
+        s = Series([1,1,2],index=['one','two','one'])
+        expected = Series([1,2],index=['one','one'])
+        result = s.drop(['two'])
+        assert_series_equal(result,expected)
+        result = s.drop('two')
+        assert_series_equal(result,expected)
+
+        expected = Series([1],index=['two'])
+        result = s.drop(['one'])
+        assert_series_equal(result,expected)
+        result = s.drop('one')
+        assert_series_equal(result,expected)
+
     def test_ix_setitem(self):
         inds = self.series.index[[3, 4, 7]]