implement handling for tuples in object dtypes

Author: flexatone

src/_arraykit.c

@@ -3592,20 +3592,22 @@ array_to_tuple_array(PyObject *Py_UNUSED(m), PyObject *a)
     }
     else { // ndim == 1, object
         while (p < p_end) {
-            tuple = PyTuple_New(1);
-            if (tuple == NULL) {
-                goto error;
-            }
-            // scalar returned in is native PyObject from object arrays
             item = *(PyObject**)PyArray_GETPTR1(input_array, i);
-            Py_INCREF(item);
-            // TODO: identify tuple
-            PyTuple_SET_ITEM(tuple, 0, item); // steals reference to item
+            Py_INCREF(item); // always incref
+            if (PyTuple_Check(item)) {
+                tuple = item; // do not double pack
+            }
+            else {
+                tuple = PyTuple_New(1);
+                if (tuple == NULL) {
+                    goto error;
+                }
+                PyTuple_SET_ITEM(tuple, 0, item); // steals reference to item
+            }
             *p++ = tuple; // assign with new ref, no incr needed
             i++;
         }
     }
-
     PyArray_CLEARFLAGS((PyArrayObject *)output, NPY_ARRAY_WRITEABLE);
     return output;
 error:
@@ -3680,10 +3682,10 @@ ATT_iternext(ATTObject *self) {
                     Py_DECREF(tuple);
                     return NULL;
                 }
-                PyTuple_SET_ITEM(tuple, j, item); // steals reference to item
+                PyTuple_SET_ITEM(tuple, j, item); // steals ref
             }
         }
-        else { // ndim == 1
+        else if (PyArray_TYPE(array) != NPY_OBJECT) { // ndim == 1, not object
             tuple = PyTuple_New(1);
             if (tuple == NULL) {
                 return NULL;
@@ -3693,7 +3695,22 @@ ATT_iternext(ATTObject *self) {
                 Py_DECREF(tuple);
                 return NULL;
             }
-            PyTuple_SET_ITEM(tuple, 0, item); // steals reference to item
+            PyTuple_SET_ITEM(tuple, 0, item); // steals ref
+        }
+        else { // ndim == 1, object
+            item = *(PyObject**)PyArray_GETPTR1(array, i);
+            Py_INCREF(item); // always incref
+            if (PyTuple_Check(item)) {
+                tuple = item; // do not double pack
+            }
+            else {
+                tuple = PyTuple_New(1);
+                if (tuple == NULL) {
+                    Py_DECREF(item);
+                    return NULL;
+                }
+                PyTuple_SET_ITEM(tuple, 0, item); // steals ref
+            }
         }
         self->pos++;
         return tuple;

test/test_util.py

@@ -286,34 +286,47 @@ def test_array_deepcopy_h(self) -> None:
             a2 = array_deepcopy(a1, ())
 
     #---------------------------------------------------------------------------
-    def test_array2d_to_array1d_1d_a(self) -> None:
+    def test_array_to_tuple_array_1d_a(self) -> None:
         a1 = np.arange(10)
         a2 = array_to_tuple_array(a1)
         self.assertEqual(a2.tolist(), [(0,), (1,), (2,), (3,), (4,), (5,), (6,), (7,), (8,), (9,)])
 
-    def test_array2d_to_array1d_1d_b(self) -> None:
+    def test_array_to_tuple_array_1d_b(self) -> None:
         a1 = np.array(['aaa', 'b', 'ccc'])
         a2 = array_to_tuple_array(a1)
         self.assertEqual(a2.tolist(), [('aaa',), ('b',), ('ccc',)])
 
-    def test_array2d_to_array1d_1d_c(self) -> None:
+    def test_array_to_tuple_array_1d_c(self) -> None:
         a1 = np.array([None, 'b', 30])
         a2 = array_to_tuple_array(a1)
         self.assertEqual(a2.tolist(), [(None,), ('b',), (30,)])
 
-    def test_array2d_to_array1d_1d_d(self) -> None:
+    def test_array_to_tuple_array_1d_d(self) -> None:
         a1 = np.array([('a', 10), ('b', 30), ('c', 5)], dtype=object)
         a2 = array_to_tuple_array(a1) # from 2d
+        self.assertEqual(a2.tolist(), [('a', 10), ('b', 30), ('c', 5)])
         a3 = array_to_tuple_array(a2) # from 1d
         self.assertEqual(a3.tolist(), [('a', 10), ('b', 30), ('c', 5)])
 
-    def test_array2d_to_array1d_1d_e(self) -> None:
+    def test_array_to_tuple_array_1d_e(self) -> None:
         a1 = np.array([True, False, True], dtype=object)
         a2 = array_to_tuple_array(a1)
         self.assertIs(a2[0][0].__class__, bool)
         self.assertEqual(a2.tolist(), [(True,), (False,), (True,)])
 
-    def test_array2d_to_array1d_b(self) -> None:
+    def test_array_to_tuple_array_1d_f(self) -> None:
+        a1 = np.array([None, None, None], dtype=object)
+        a1[0] = 3
+        a1[1] = ('a', 30)
+        a1[2] = (None, True, 90000000)
+
+        a2 = array_to_tuple_array(a1)
+        self.assertEqual(a2.tolist(), [(3,), ('a', 30), (None, True, 90000000)])
+
+        a3 = array_to_tuple_array(a2)
+        self.assertEqual(a3.tolist(), [(3,), ('a', 30), (None, True, 90000000)])
+
+    def test_array_to_tuple_array_b(self) -> None:
         a1 = np.arange(10, dtype=np.int64).reshape(5, 2)
         result = array_to_tuple_array(a1)
         assert isinstance(result[0], tuple)
@@ -323,18 +336,18 @@ def test_array2d_to_array1d_b(self) -> None:
         self.assertEqual(tuple(result), ((0, 1), (2, 3), (4, 5), (6, 7), (8, 9)))
 
 
-    def test_array2d_to_array1d_c(self) -> None:
+    def test_array_to_tuple_array_c(self) -> None:
         a1 = np.array([["a", "b"], ["ccc", "ddd"], ["ee", "ff"]])
         a2 = array_to_tuple_array(a1)
         self.assertEqual(a2.tolist(), [('a', 'b'), ('ccc', 'ddd'), ('ee', 'ff')])
 
-    def test_array2d_to_array1d_d(self) -> None:
+    def test_array_to_tuple_array_d(self) -> None:
         a1 = np.array([[3, 5], [10, 20], [7, 2]], dtype=np.uint8)
         a2 = array_to_tuple_array(a1)
         self.assertEqual(a2.tolist(), [(3, 5), (10, 20), (7, 2)])
         self.assertIs(type(a2[0][0]), np.uint8)
 
-    def test_array2d_to_array1d_e(self) -> None:
+    def test_array_to_tuple_array_e(self) -> None:
         a1 = np.arange(20, dtype=np.int64).reshape(4, 5)
         result = array_to_tuple_array(a1)
         self.assertEqual(result.tolist(), [(0, 1, 2, 3, 4), (5, 6, 7, 8, 9), (10, 11, 12, 13, 14), (15, 16, 17, 18, 19)])