Batch.to_dict should be a rremain by default a recursive conversion

test/base/test_batch.py

@@ -655,7 +655,7 @@ def test_to_dict_nested_batch_no_recurse() -> None:
         nested_batch = Batch(c=3)
         batch = Batch(a=1, b=nested_batch)
         expected = {"a": np.asanyarray(1), "b": nested_batch}
-        assert not DeepDiff(batch.to_dict(), expected)
+        assert not DeepDiff(batch.to_dict(recurse=False), expected)
 
     @staticmethod
     def test_to_dict_nested_batch_recurse() -> None:

tianshou/data/batch.py

@@ -405,7 +405,7 @@ def split(
         """
         ...
 
-    def to_dict(self, recurse: bool = False) -> dict[str, Any]:
+    def to_dict(self, recurse: bool = True) -> dict[str, Any]:
         ...
 
     def to_list_of_dicts(self) -> list[dict[str, Any]]:
@@ -442,7 +442,7 @@ def __init__(
             # Feels like kwargs could be just merged into batch_dict in the beginning
             self.__init__(kwargs, copy=copy)  # type: ignore
 
-    def to_dict(self, recurse: bool = False) -> dict[str, Any]:
+    def to_dict(self, recurse: bool = True) -> dict[str, Any]:
         result = {}
         for k, v in self.__dict__.items():
             if recurse and isinstance(v, Batch):