Implement shape inference for boolean advanced indexing

Author: ricardoV94

pytensor/tensor/subtensor.py

@@ -20,15 +20,11 @@
 from pytensor.printing import Printer, pprint, set_precedence
 from pytensor.scalar.basic import ScalarConstant
 from pytensor.tensor import _get_vector_length, as_tensor_variable, get_vector_length
-from pytensor.tensor.basic import alloc, get_underlying_scalar_constant_value
+from pytensor.tensor.basic import alloc, get_underlying_scalar_constant_value, nonzero
 from pytensor.tensor.elemwise import DimShuffle
-from pytensor.tensor.exceptions import (
-    AdvancedIndexingError,
-    NotScalarConstantError,
-    ShapeError,
-)
+from pytensor.tensor.exceptions import AdvancedIndexingError, NotScalarConstantError
 from pytensor.tensor.math import clip
-from pytensor.tensor.shape import Reshape, specify_broadcastable
+from pytensor.tensor.shape import Reshape, shape_i, specify_broadcastable
 from pytensor.tensor.type import (
     TensorType,
     bscalar,
@@ -2585,26 +2581,47 @@ def R_op(self, inputs, eval_points):
         return self.make_node(eval_points[0], *inputs[1:]).outputs
 
     def infer_shape(self, fgraph, node, ishapes):
-        indices = node.inputs[1:]
-        index_shapes = list(ishapes[1:])
-        for i, idx in enumerate(indices):
-            if (
+        def is_bool_index(idx):
+            return (
                 isinstance(idx, (np.bool_, bool))
                 or getattr(idx, "dtype", None) == "bool"
-            ):
-                raise ShapeError(
-                    "Shape inference for boolean indices is not implemented"
+            )
+
+        indices = node.inputs[1:]
+        index_shapes = []
+        for idx, ishape in zip(indices, ishapes[1:]):
+            # Mixed bool indexes are converted to nonzero entries
+            if is_bool_index(idx):
+                index_shapes.extend(
+                    (shape_i(nz_dim, 0, fgraph=fgraph),) for nz_dim in nonzero(idx)
                 )
             # The `ishapes` entries for `SliceType`s will be None, and
             # we need to give `indexed_result_shape` the actual slices.
-            if isinstance(getattr(idx, "type", None), SliceType):
-                index_shapes[i] = idx
+            elif isinstance(getattr(idx, "type", None), SliceType):
+                index_shapes.append(idx)
+            else:
+                index_shapes.append(ishape)
 
-        res_shape = indexed_result_shape(
-            ishapes[0], index_shapes, indices_are_shapes=True
+        res_shape = list(
+            indexed_result_shape(ishapes[0], index_shapes, indices_are_shapes=True)
         )
+
+        adv_indices = [idx for idx in indices if not is_basic_idx(idx)]
+        bool_indices = [idx for idx in adv_indices if is_bool_index(idx)]
+
+        # Special logic when the only advanced index group is of bool type.
+        # We can replace the nonzeros by a sum of the whole bool variable.
+        if len(bool_indices) == 1 and len(adv_indices) == 1:
+            [bool_index] = bool_indices
+            # Find the output dim associated with the bool index group
+            # Because there are no more advanced index groups, there is exactly
+            # one output dim per index variable up to the bool group.
+            # Note: Scalar integer indexing counts as advanced indexing.
+            start_dim = indices.index(bool_index)
+            res_shape[start_dim] = bool_index.sum()
+
         assert node.outputs[0].ndim == len(res_shape)
-        return [list(res_shape)]
+        return [res_shape]
 
     def perform(self, node, inputs, out_):
         (out,) = out_

tests/tensor/test_subtensor.py

@@ -63,6 +63,7 @@
     tensor,
     tensor3,
     tensor4,
+    tensor5,
     vector,
 )
 from pytensor.tensor.type_other import NoneConst, SliceConstant, make_slice, slicetype
@@ -2150,6 +2151,12 @@ def fun(x, y):
 
 
 class TestInferShape(utt.InferShapeTester):
+    @staticmethod
+    def random_bool_mask(shape, rng=None):
+        if rng is None:
+            rng = np.random.default_rng()
+        return rng.binomial(n=1, p=0.5, size=shape).astype(bool)
+
     def test_IncSubtensor(self):
         admat = dmatrix()
         bdmat = dmatrix()
@@ -2439,25 +2446,84 @@ def test_AdvancedSubtensor_bool(self):
         n = dmatrix()
         n_val = np.arange(6).reshape((2, 3))
 
-        # infer_shape is not implemented, but it should not crash
         self._compile_and_check(
             [n],
             [n[n[:, 0] > 2, n[0, :] > 2]],
             [n_val],
             AdvancedSubtensor,
-            check_topo=False,
         )
         self._compile_and_check(
             [n],
             [n[n[:, 0] > 2]],
             [n_val],
             AdvancedSubtensor,
-            check_topo=False,
+        )
+        self._compile_and_check(
+            [n],
+            [n[:, np.array([True, False, True])]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            [n[np.array([False, False]), 1:]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            [n[np.array([True, True]), 0]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            [n[self.random_bool_mask(n_val.shape)]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            [n[None, self.random_bool_mask(n_val.shape), None]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            [n[slice(5, None), self.random_bool_mask(n_val.shape[1])]],
+            [n_val],
+            AdvancedSubtensor,
         )
 
         abs_res = n[~isinf(n)]
         assert abs_res.type.shape == (None,)
 
+    def test_AdvancedSubtensor_bool_mixed(self):
+        n = tensor5("x", dtype="float64")
+        shape = (18, 3, 4, 5, 6)
+        n_val = np.arange(np.prod(shape)).reshape(shape)
+        self._compile_and_check(
+            [n],
+            # Consecutive advanced index
+            [n[1:, self.random_bool_mask((3, 4)), 0, 1:]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            # Non-consecutive advanced index
+            [n[1:, self.random_bool_mask((3, 4)), 1:, 0]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+        self._compile_and_check(
+            [n],
+            # Non-consecutive advanced index
+            [n[1:, self.random_bool_mask((3,)), 1:, None, np.zeros((6, 1), dtype=int)]],
+            [n_val],
+            AdvancedSubtensor,
+        )
+
 
 @config.change_flags(compute_test_value="raise")
 def test_basic_shape():