REF: dont use compute_reduction (#34913)

Author: jbrockmendel

pandas/core/apply.py

@@ -220,13 +220,7 @@ def apply_empty_result(self):
 
     def apply_raw(self):
         """ apply to the values as a numpy array """
-        result, reduction_success = libreduction.compute_reduction(
-            self.values, self.f, axis=self.axis
-        )
-
-        # We expect np.apply_along_axis to give a two-dimensional result, or raise.
-        if not reduction_success:
-            result = np.apply_along_axis(self.f, self.axis, self.values)
+        result = np.apply_along_axis(self.f, self.axis, self.values)
 
         # TODO: mixed type case
         if result.ndim == 2:

pandas/tests/frame/test_apply.py

@@ -745,9 +745,6 @@ def non_reducing_function(row):
             df.apply(func, axis=1)
             assert names == list(df.index)
 
-    @pytest.mark.xfail(
-        reason="The 'run once' enhancement for apply_raw not implemented yet."
-    )
     def test_apply_raw_function_runs_once(self):
         # https://github.com/pandas-dev/pandas/issues/34506