Fix Batch.__eq__ to work also for scalar values

test/base/test_batch.py

@@ -544,6 +544,28 @@ def test_nested_shapes_different() -> None:
         batch2 = Batch(a=Batch(a=[1, 4]), b=[4, 5])
         assert batch1 != batch2
 
+    @staticmethod
+    def test_array_scalars() -> None:
+        batch1 = Batch(a={"b": 1})
+        batch2 = Batch(a={"b": 1})
+        assert batch1 == batch2
+
+        batch3 = Batch(a={"c": 2})
+        assert batch1 != batch3
+
+        batch4 = Batch(b={"b": 1})
+        assert batch1 != batch4
+
+        batch5 = Batch(a={"b": 10})
+        assert batch1 != batch5
+
+        batch6 = Batch(a={"b": [1]})
+        assert batch1 == batch6
+
+        batch7 = Batch(a=1, b=5)
+        batch8 = Batch(a=1, b=5)
+        assert batch7 == batch8
+
     @staticmethod
     def test_slice_equal() -> None:
         batch1 = Batch(a=[1, 2, 3])

tianshou/data/batch.py

@@ -678,6 +678,16 @@ def __eq__(self, other: Any) -> bool:
 
         this_batch_no_torch_tensor: Batch = Batch.to_numpy(self)
         other_batch_no_torch_tensor: Batch = Batch.to_numpy(other)
+        # DeepDiff 7.0.1 cannot compare 0-dimensional arrays
+        # so, we ensure with this transform that all array values have at least 1 dim
+        this_batch_no_torch_tensor.apply_values_transform(
+            values_transform=np.atleast_1d,
+            inplace=True,
+        )
+        other_batch_no_torch_tensor.apply_values_transform(
+            values_transform=np.atleast_1d,
+            inplace=True,
+        )
         this_dict = this_batch_no_torch_tensor.to_dict(recursive=True)
         other_dict = other_batch_no_torch_tensor.to_dict(recursive=True)