Fix 'to_tensor' dtype/device forwarding for Batch over Batch. (#68)

* Fix Batch to_torch method not updating dtype/device of already converted data.

* Fix dtype/device to forwarded by to_tensor for Batch over Batch.

* Add Unit test to check to_torch dtype/device recursive forwarding.

* Batch UT check accessing data using both dict and class style.

* Fix utils to_tensor dtype/device forwarding. Add Unit tests.

* Fix UT.

Co-authored-by: Alexis Duburcq <alexis.duburcq@wandercraft.eu>
Co-authored-by: n+e <463003665@qq.com>

test/base/test_batch.py

@@ -3,11 +3,12 @@ import pickle
 import torch
 import numpy as np
 
-from tianshou.data import Batch
+from tianshou.data import Batch, to_torch
 
 
 def test_batch():
     batch = Batch(obs=[0], np=np.zeros([3, 4]))
+    assert batch.obs == batch["obs"]
     batch.obs = [1]
     assert batch.obs == [1]
     batch.append(batch)
@@ -31,6 +32,45 @@ def test_batch_over_batch():
     assert batch2[-1].b.b == 0
 
 
+def test_batch_over_batch_to_torch():
+    batch = Batch(
+        a=np.ones((1,), dtype=np.float64),
+        b=Batch(
+            c=np.ones((1,), dtype=np.float64),
+            d=torch.ones((1,), dtype=torch.float64)
+        )
+    )
+    batch.to_torch()
+    assert isinstance(batch.a, torch.Tensor)
+    assert isinstance(batch.b.c, torch.Tensor)
+    assert isinstance(batch.b.d, torch.Tensor)
+    assert batch.a.dtype == torch.float64
+    assert batch.b.c.dtype == torch.float64
+    assert batch.b.d.dtype == torch.float64
+    batch.to_torch(dtype=torch.float32)
+    assert batch.a.dtype == torch.float32
+    assert batch.b.c.dtype == torch.float32
+    assert batch.b.d.dtype == torch.float32
+
+
+def test_utils_to_torch():
+    batch = Batch(
+        a=np.ones((1,), dtype=np.float64),
+        b=Batch(
+            c=np.ones((1,), dtype=np.float64),
+            d=torch.ones((1,), dtype=torch.float64)
+        )
+    )
+    a_torch_float = to_torch(batch.a, dtype=torch.float32)
+    assert a_torch_float.dtype == torch.float32
+    a_torch_double = to_torch(batch.a, dtype=torch.float64)
+    assert a_torch_double.dtype == torch.float64
+    batch_torch_float = to_torch(batch, dtype=torch.float32)
+    assert batch_torch_float.a.dtype == torch.float32
+    assert batch_torch_float.b.c.dtype == torch.float32
+    assert batch_torch_float.b.d.dtype == torch.float32
+
+
 def test_batch_pickle():
     batch = Batch(obs=Batch(a=0.0, c=torch.Tensor([1.0, 2.0])),
                   np=np.zeros([3, 4]))
@@ -42,14 +82,12 @@ def test_batch_pickle():
 
 def test_batch_from_to_numpy_without_copy():
     batch = Batch(a=np.ones((1,)), b=Batch(c=np.ones((1,))))
-    a_mem_addr_orig = batch["a"].__array_interface__['data'][0]
+    a_mem_addr_orig = batch.a.__array_interface__['data'][0]
-    c_mem_addr_orig = batch["b"]["c"].__array_interface__['data'][0]
+    c_mem_addr_orig = batch.b.c.__array_interface__['data'][0]
     batch.to_torch()
-    assert isinstance(batch["a"], torch.Tensor)
-    assert isinstance(batch["b"]["c"], torch.Tensor)
     batch.to_numpy()
-    a_mem_addr_new = batch["a"].__array_interface__['data'][0]
+    a_mem_addr_new = batch.a.__array_interface__['data'][0]
-    c_mem_addr_new = batch["b"]["c"].__array_interface__['data'][0]
+    c_mem_addr_new = batch.b.c.__array_interface__['data'][0]
     assert a_mem_addr_new == a_mem_addr_orig
     assert c_mem_addr_new == c_mem_addr_orig
 

tianshou/data/batch.py

@@ -183,19 +183,36 @@ class Batch:
 
     def to_torch(self,
                  dtype: Optional[torch.dtype] = None,
-                 device: Union[str, int] = 'cpu'
+                 device: Union[str, int, torch.device] = 'cpu'
                  ) -> None:
         """Change all numpy.ndarray to torch.Tensor. This is an inplace
         operation.
         """
+        if not isinstance(device, torch.device):
+            device = torch.device(device)
+
         for k, v in self.__dict__.items():
             if isinstance(v, np.ndarray):
                 v = torch.from_numpy(v).to(device)
                 if dtype is not None:
                     v = v.type(dtype)
                 self.__dict__[k] = v
+            if isinstance(v, torch.Tensor):
+                if dtype is not None and v.dtype != dtype:
+                    must_update_tensor = True
+                elif v.device.type != device.type:
+                    must_update_tensor = True
+                elif device.index is not None and \
+                        device.index != v.device.index:
+                    must_update_tensor = True
+                else:
+                    must_update_tensor = False
+                if must_update_tensor:
+                    if dtype is not None:
+                        v = v.type(dtype)
+                    self.__dict__[k] = v.to(device)
             elif isinstance(v, Batch):
-                v.to_torch()
+                v.to_torch(dtype, device)
 
     def append(self, batch: 'Batch') -> None:
         """Append a :class:`~tianshou.data.Batch` object to current batch."""

tianshou/data/utils.py

@@ -28,9 +28,13 @@ def to_torch(x: Union[torch.Tensor, dict, Batch, np.ndarray],
         x = torch.from_numpy(x).to(device)
         if dtype is not None:
             x = x.type(dtype)
+    if isinstance(x, torch.Tensor):
+        if dtype is not None:
+            x = x.type(dtype)
+        x = x.to(device)
     elif isinstance(x, dict):
         for k, v in x.items():
             x[k] = to_torch(v, dtype, device)
     elif isinstance(x, Batch):
-        x.to_torch()
+        x.to_torch(dtype, device)
     return x