ENH: attach name to Series on axis=1 in DataFrame.apply, #983

pandas-dev · Apr 10, 2012 · 5721a0c · 5721a0c
1 parent 91802b1
commit 5721a0c
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Showing 2 changed files with 19 additions and 2 deletions.
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
@@ -3095,7 +3095,7 @@ def _apply_standard(self, func, axis, ignore_failures=False):
         elif axis == 1:
             res_index = self.index
             res_columns = self.columns
-            series_gen = ((i, Series(v, self.columns))
+            series_gen = ((i, Series(v, self.columns, name=i))
                           for i, v in izip(self.index, self.values))
 
         results = {}
@@ -3125,7 +3125,8 @@ def _apply_standard(self, func, axis, ignore_failures=False):
             else:
                 index = None
 
-            result = self._constructor(data=results, index=index)
+            result = self._constructor(data=results, index=index,
+                                       columns=res_index)
 
             if axis == 1:
                 result = result.T

diff --git a/pandas/tests/test_frame.py b/pandas/tests/test_frame.py
@@ -3904,6 +3904,22 @@ def test_apply_attach_name(self):
         expected = Series(self.frame.index, index=self.frame.index)
         assert_series_equal(result, expected)
 
+        # non-reductions
+        result = self.frame.apply(lambda x: np.repeat(x.name, len(x)))
+        expected = DataFrame(np.tile(self.frame.columns,
+                                     (len(self.frame.index), 1)),
+                             index=self.frame.index,
+                             columns=self.frame.columns)
+        assert_frame_equal(result, expected)
+
+        result = self.frame.apply(lambda x: np.repeat(x.name, len(x)),
+                                  axis=1)
+        expected = DataFrame(np.tile(self.frame.index,
+                                     (len(self.frame.columns), 1)).T,
+                             index=self.frame.index,
+                             columns=self.frame.columns)
+        assert_frame_equal(result, expected)
+
     def test_applymap(self):
         applied = self.frame.applymap(lambda x: x * 2)
         assert_frame_equal(applied, self.frame * 2)