Apply func non roundtrippable seq

CHANGELOG.md

@@ -11,7 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
--
+- Apply func non round-trippable seq ([#250](https://github.com/Lightning-AI/utilities/pull/250))
 
 
 ### Changed

src/lightning_utilities/core/apply_func.py

@@ -20,6 +20,14 @@ def is_dataclass_instance(obj: object) -> bool:
     return dataclasses.is_dataclass(obj) and not isinstance(obj, type)
 
 
+def can_roundtrip_sequence(obj: Sequence) -> bool:
+    """Check if sequence can be roundtripped."""
+    try:
+        return obj == type(obj)(list(obj))  # type: ignore[call-arg]
+    except (TypeError, ValueError):
+        return False
+
+
 def apply_to_collection(
     data: Any,
     dtype: Union[type, Any, Tuple[Union[type, Any]]],
@@ -118,7 +126,7 @@ def _apply_to_collection_slow(
         return elem_type(OrderedDict(out))
 
     is_namedtuple_ = is_namedtuple(data)
-    is_sequence = isinstance(data, Sequence) and not isinstance(data, str)
+    is_sequence = isinstance(data, Sequence) and not isinstance(data, str) and can_roundtrip_sequence(data)
     if is_namedtuple_ or is_sequence:
         out = []
         for d in data:

tests/unittests/core/test_apply_func.py

@@ -359,3 +359,13 @@ class Foo:
     foo = Foo(0)
     result = apply_to_collection(foo, int, lambda x: x + 1, allow_frozen=True)
     assert foo == result
+
+
+def test_apply_to_collection_non_roundtrippable_sequence():
+    class NonRoundtrippableSequence(list):
+        def __init__(self, x: int):
+            super().__init__(range(int(x)))
+
+    val = NonRoundtrippableSequence(3)
+    result = apply_to_collection(val, int, lambda x: x + 1)
+    assert val == result