[Fix] use 2d empty arrays instead of 1d empty arrays as defaults

Author: balbasty

spm/__wrapper__.py

@@ -157,10 +157,6 @@ def _import_initialize():
 # ----------------------------------------------------------------------
 
 
-_NP_VERSION = tuple(map(int, np.__version__.split(".")[:2]))
-_NP_HAS_COPY = not (_NP_VERSION < (2, 1))
-
-
 def _copy_if_needed(out, inp, copy=None) -> np.ndarray:
     """Fallback implementation for asarray(*, copy: bool)"""
     if (
@@ -212,6 +208,11 @@ def _matlab_array_types():
         return {}
 
 
+def _empty_array() -> "Array":
+    """Matlab's default cell/struct elements are 0x0 arrays."""
+    return Array.from_shape([0, 0])
+
+
 # ----------------------------------------------------------------------
 # Types
 # ----------------------------------------------------------------------
@@ -534,7 +535,7 @@ def _finalize(self):
 
         if self._future is None:
             # FIXME: I am not entirely sure this should ever happen
-            self._future = Array.from_any([])
+            self._future = _empty_array()
 
         # if future array is wrapped, unwrap it
         if isinstance(self._future, WrappedDelayedArray):
@@ -1704,19 +1705,14 @@ class Cell(_ListMixin, WrappedArray):
 
     @classmethod
     def _DEFAULT(cls, shape: list = ()) -> np.ndarray:
-        # if len(shape) == 0:
-        #     out = np.array(None)
-        #     out[()] = Array.from_any([])
-        #     return out
-
         data = np.empty(shape, dtype=object)
         opt = dict(
             flags=['refs_ok', 'zerosize_ok'],
             op_flags=['writeonly', 'no_broadcast']
         )
         with np.nditer(data, **opt) as iter:
             for elem in iter:
-                elem[()] = Array.from_any([])
+                elem[()] = _empty_array()
         return data
 
     def _fill_default(self):
@@ -1725,7 +1721,7 @@ def _fill_default(self):
                    op_flags=['writeonly', 'no_broadcast'])
         with np.nditer(arr, **opt) as iter:
             for elem in iter:
-                elem[()] = Array.from_any([])
+                elem[()] = _empty_array()
         return self
 
     def __new__(cls, *args, **kwargs) -> "Cell":
@@ -2111,7 +2107,7 @@ def __getitem__(self, key):
             opt = dict(flags=['refs_ok', 'zerosize_ok'], op_flags=['readonly'])
             with np.nditer(arr, **opt) as iter:
                 for elem in iter:
-                    elem.item().setdefault(key, Array.from_any([]))
+                    elem.item().setdefault(key, _empty_array())
 
             # NOTE
             #   We then defer to `as_dict`
@@ -2206,7 +2202,7 @@ def setdefault(self, key, value=None):
             for elem in iter:
                 item = elem.item()
                 if value is None:
-                    value = Array.from_any([])
+                    value = _empty_array()
                 else:
                     value = MatlabType.from_any(value)
                 item.setdefault(key, value)
@@ -2604,7 +2600,7 @@ def _ensure_defaults_are_set(self, keys=None):
             if keys:
                 item: dict = arr.item()
                 for key in keys:
-                    item.setdefault(key, Array.from_any([]))
+                    item.setdefault(key, _empty_array())
 
         if keys is None:
             keys = self._allkeys()
@@ -2616,7 +2612,7 @@ def _ensure_defaults_are_set(self, keys=None):
             for elem in iter:
                 item: dict = elem.item()
                 for key in keys:
-                    item.setdefault(key, Array.from_any([]))
+                    item.setdefault(key, _empty_array())
 
     # --------------
     # Bracket syntax

tests/test_cell.py

@@ -463,7 +463,7 @@ def test_cell_indexing_1d(self):
         c[3] = 9  # insert new element
         self.assertEqual(c.tolist(), [7, 2, 8, 9])
         c[5] = 11  # insert new element
-        self.assertTrue(isinstance(c[4], Array) and c[4].shape == (0,))
+        self.assertTrue(isinstance(c[4], Array) and c[4].size == 0)
         self.assertTrue(c[5] == 11)
 
         # __delitem__

tests/test_implicit.py

@@ -19,13 +19,13 @@ def test_array(self):
     def test_cell(self):
         x = Cell()
         x[2] = 3
-        self.assertEqual(x[0].shape, (0,))
-        self.assertEqual(x[1].shape, (0,))
+        self.assertEqual(x[0].shape, (0, 0))
+        self.assertEqual(x[1].shape, (0, 0))
         self.assertEqual(x[2], 3)
 
         x = Cell()
         x[1:3] = [2, 3]
-        self.assertEqual(x[0].shape, (0,))
+        self.assertEqual(x[0].shape, (0, 0))
         self.assertListEqual(x[1:3].tolist(), [2, 3])
 
         self.assertRaises(IndexError, lambda: Cell()[2] * 2)
@@ -39,7 +39,7 @@ def test_struct(self):
         x[1] = {"a": 3}
         self.assertTrue(x.shape == (2,))
         self.assertEqual(x[1].a, 3)
-        self.assertTrue(x[0].a.shape == (0,))
+        self.assertTrue(x[0].a.shape == (0, 0))
 
         self.assertRaises(AttributeError, lambda: Struct().a * 2)
         self.assertRaises(KeyError, lambda: Struct()["a"] * 2)

tests/test_struct.py

@@ -124,11 +124,11 @@ def test_struct_as_array_after_initialization(self):
 
         # Unspecified elements are empty arrays
         self.assertIsInstance(self.struct[0].baz, Array)
-        self.assertTupleEqual(self.struct[0].baz.shape, (0,))
+        self.assertTupleEqual(self.struct[0].baz.shape, (0, 0))
         self.assertIsInstance(self.struct[1].foo, Array)
-        self.assertTupleEqual(self.struct[1].foo.shape, (0,))
+        self.assertTupleEqual(self.struct[1].foo.shape, (0, 0))
         self.assertIsInstance(self.struct[1].bar, Array)
-        self.assertTupleEqual(self.struct[1].bar.shape, (0,))
+        self.assertTupleEqual(self.struct[1].bar.shape, (0, 0))
 
     def test_struct_from_matlab(self):
         # Construct a struct in Matlab