BUG: Series.align resets name when fill_value is specified

doc/source/whatsnew/v0.17.0.txt

@@ -73,9 +73,14 @@ Bug Fixes
 - Bug in display datetimes with mixed frequencies uniformly; display 'ms' datetimes to the proper precision. (:issue:`10170`)
 
 
+
 - Bug in ``DatetimeIndex`` and ``TimedeltaIndex`` names are lost after timedelta arithmetics ( :issue:`9926`)
 
 - Bug in `Series.plot(label="LABEL")` not correctly setting the label (:issue:`10119`)
+
 - Bug in `plot` not defaulting to matplotlib `axes.grid` setting (:issue:`9792`)
 
+- Bug in ``Series.align`` resets ``name`` when ``fill_value`` is specified (:issue:`10067`)
+
+
 

pandas/core/generic.py

@@ -3365,11 +3365,10 @@ def _align_series(self, other, join='outer', axis=None, level=None,
                                                          level=level,
                                                          return_indexers=True)
 
-            left_result = self._reindex_indexer(join_index, lidx, copy)
-            right_result = other._reindex_indexer(join_index, ridx, copy)
+            left = self._reindex_indexer(join_index, lidx, copy)
+            right = other._reindex_indexer(join_index, ridx, copy)
 
         else:
-
             # one has > 1 ndim
             fdata = self._data
             if axis == 0:
@@ -3399,23 +3398,19 @@ def _align_series(self, other, join='outer', axis=None, level=None,
             if copy and fdata is self._data:
                 fdata = fdata.copy()
 
-            left_result = DataFrame(fdata)
+            left = DataFrame(fdata)
 
             if ridx is None:
-                right_result = other
+                right = other
             else:
-                right_result = other.reindex(join_index, level=level)
+                right = other.reindex(join_index, level=level)
 
         # fill
         fill_na = notnull(fill_value) or (method is not None)
         if fill_na:
-            return (left_result.fillna(fill_value, method=method, limit=limit,
-                                       axis=fill_axis),
-                    right_result.fillna(fill_value, method=method,
-                                        limit=limit))
-        else:
-            return (left_result.__finalize__(self),
-                    right_result.__finalize__(other))
+            left = left.fillna(fill_value, method=method, limit=limit, axis=fill_axis)
+            right = right.fillna(fill_value, method=method, limit=limit)
+        return (left.__finalize__(self), right.__finalize__(other))
 
     _shared_docs['where'] = ("""
         Return an object of same shape as self and whose corresponding

pandas/tests/test_series.py

@@ -5932,19 +5932,26 @@ def _check_align(a, b, how='left', fill=None):
 
             assert_series_equal(aa, ea)
             assert_series_equal(ab, eb)
+            self.assertEqual(aa.name, 'ts')
+            self.assertEqual(ea.name, 'ts')
+            self.assertEqual(ab.name, 'ts')
+            self.assertEqual(eb.name, 'ts')
 
         for kind in JOIN_TYPES:
             _check_align(self.ts[2:], self.ts[:-5], how=kind)
             _check_align(self.ts[2:], self.ts[:-5], how=kind, fill=-1)
 
             # empty left
             _check_align(self.ts[:0], self.ts[:-5], how=kind)
+            _check_align(self.ts[:0], self.ts[:-5], how=kind, fill=-1)
 
             # empty right
             _check_align(self.ts[:-5], self.ts[:0], how=kind)
+            _check_align(self.ts[:-5], self.ts[:0], how=kind, fill=-1)
 
             # both empty
             _check_align(self.ts[:0], self.ts[:0], how=kind)
+            _check_align(self.ts[:0], self.ts[:0], how=kind, fill=-1)
 
     def test_align_fill_method(self):
         def _check_align(a, b, how='left', method='pad', limit=None):