Implement basic Alloc Ops in PyTorch

Author: ricardoV94

pytensor/link/pytorch/dispatch/basic.py

@@ -6,6 +6,7 @@
 from pytensor.graph.fg import FunctionGraph
 from pytensor.link.utils import fgraph_to_python
 from pytensor.raise_op import CheckAndRaise
+from pytensor.tensor.basic import Alloc, AllocEmpty, ARange
 
 
 @singledispatch
@@ -58,3 +59,33 @@ def deepcopyop(x):
         return x.clone()
 
     return deepcopyop
+
+
+@pytorch_funcify.register(AllocEmpty)
+def pytorch_funcify_AllocEmpty(op, **kwargs):
+    dtype = getattr(torch, op.dtype)
+
+    def alloc_empty(*shape):
+        return torch.empty(shape, dtype=dtype)
+
+    return alloc_empty
+
+
+@pytorch_funcify.register(Alloc)
+def pytorch_funcify_alloc(op, **kwargs):
+    def alloc(value, *shape):
+        out = torch.empty(shape, dtype=value.dtype)
+        out[...] = value  # broadcast value to shape of out
+        return out
+
+    return alloc
+
+
+@pytorch_funcify.register(ARange)
+def pytorch_funcify_arange(op, **kwargs):
+    dtype = getattr(torch, op.dtype)
+
+    def arange(start, stop, step):
+        return torch.arange(start, stop, step, dtype=dtype)
+
+    return arange

tests/link/pytorch/test_basic.py

@@ -12,6 +12,7 @@
 from pytensor.graph.fg import FunctionGraph
 from pytensor.graph.op import Op
 from pytensor.raise_op import CheckAndRaise
+from pytensor.tensor import alloc, arange, as_tensor, empty
 from pytensor.tensor.type import scalar, vector
 
 
@@ -191,7 +192,7 @@ def test_shared_updates(device):
         assert isinstance(a.get_value(), np.ndarray)
 
 
-def test_pytorch_checkandraise():
+def test_checkandraise():
     check_and_raise = CheckAndRaise(AssertionError, "testing")
 
     x = scalar("x")
@@ -203,3 +204,34 @@ def test_pytorch_checkandraise():
     with pytest.raises(AssertionError, match="testing"):
         y_fn(0.0)
     assert y_fn(4).item() == 4
+
+
+def test_alloc_and_empty():
+    dim0 = as_tensor(5, dtype="int64")
+    dim1 = scalar("dim1", dtype="int64")
+
+    out = empty((dim0, dim1, 3), dtype="float32")
+    fn = function([dim1], out, mode=pytorch_mode)
+    res = fn(7)
+    assert res.shape == (5, 7, 3)
+    assert res.dtype == torch.float32
+
+    v = vector("v", shape=(3,), dtype="float64")
+    out = alloc(v, (dim0, dim1, 3))
+    compare_pytorch_and_py(
+        FunctionGraph([v, dim1], [out]),
+        [np.array([1, 2, 3]), np.array(7)],
+    )
+
+
+def test_arange():
+    start = scalar("start", dtype="int64")
+    stop = scalar("stop", dtype="int64")
+    step = scalar("step", dtype="int64")
+
+    out = arange(start, stop, step, dtype="int16")
+
+    compare_pytorch_and_py(
+        FunctionGraph([start, stop, step], [out]),
+        [np.array(1), np.array(10), np.array(2)],
+    )