BUG: ufunc: The refactored reduction code didn't work with object arrays

mwhansen · May 8, 2012 · c869d12 · c869d12
1 parent 084eed7
commit c869d12
Show file tree

Hide file tree

Showing 2 changed files with 36 additions and 6 deletions.
diff --git a/numpy/core/src/umath/ufunc_object.c b/numpy/core/src/umath/ufunc_object.c
@@ -2831,10 +2831,24 @@ PyUFunc_Reduce(PyUFuncObject *ufunc, PyArrayObject *arr, PyArrayObject *out,
         case PyUFunc_Zero:
             assign_identity = &assign_reduce_identity_zero;
             reorderable = 1;
+            /*
+             * The identity for a dynamic dtype like
+             * object arrays can't be used in general
+             */
+            if (PyArray_ISOBJECT(arr) && PyArray_SIZE(arr) != 0) {
+                assign_identity = NULL;
+            }
             break;
         case PyUFunc_One:
             assign_identity = &assign_reduce_identity_one;
             reorderable = 1;
+            /*
+             * The identity for a dynamic dtype like
+             * object arrays can't be used in general
+             */
+            if (PyArray_ISOBJECT(arr) && PyArray_SIZE(arr) != 0) {
+                assign_identity = NULL;
+            }
             break;
         case PyUFunc_None:
             reorderable = 0;

diff --git a/numpy/core/tests/test_ufunc.py b/numpy/core/tests/test_ufunc.py
@@ -507,13 +507,29 @@ def test_object_logical(self):
         assert_equal(np.logical_or.reduce(a), 3)
         assert_equal(np.logical_and.reduce(a), None)
 
+    def test_object_array_reduction(self):
+        # Reductions on object arrays
+        a = np.array(['a', 'b', 'c'], dtype=object)
+        assert_equal(np.sum(a), 'abc')
+        assert_equal(np.max(a), 'c')
+        assert_equal(np.min(a), 'a')
+        a = np.array([True, False, True], dtype=object)
+        assert_equal(np.sum(a), 2)
+        assert_equal(np.prod(a), 0)
+        assert_equal(np.any(a), True)
+        assert_equal(np.all(a), False)
+        assert_equal(np.max(a), True)
+        assert_equal(np.min(a), False)
+
     def test_zerosize_reduction(self):
-        assert_equal(np.sum([]), 0)
-        assert_equal(np.prod([]), 1)
-        assert_equal(np.any([]), False)
-        assert_equal(np.all([]), True)
-        assert_raises(ValueError, np.max, [])
-        assert_raises(ValueError, np.min, [])
+        # Test with default dtype and object dtype
+        for a in [[], np.array([], dtype=object)]:
+            assert_equal(np.sum(a), 0)
+            assert_equal(np.prod(a), 1)
+            assert_equal(np.any(a), False)
+            assert_equal(np.all(a), True)
+            assert_raises(ValueError, np.max, a)
+            assert_raises(ValueError, np.min, a)
 
     def test_axis_out_of_bounds(self):
         a = np.array([False, False])