refactor(framework:skip) Add function to unflatten dicts (#3974)

src/py/flwr/common/config.py

@@ -141,6 +141,23 @@ def flatten_dict(
  return dict(items)
 
 
+def unflatten_dict(flat_dict: Dict[str, Any]) -> Dict[str, Any]:
+ """Unflatten a dict with keys containing separators into a nested dict."""
+ unflattened_dict: Dict[str, Any] = {}
+ separator: str = "."
+
+ for key, value in flat_dict.items():
+ parts = key.split(separator)
+ d = unflattened_dict
+ for part in parts[:-1]:
+ if part not in d:
+ d[part] = {}
+ d = d[part]
+ d[parts[-1]] = value
+
+ return unflattened_dict
+
+
 def parse_config_args(
  config: Optional[List[str]],
  separator: str = ",",

src/py/flwr/common/config_test.py

@@ -30,6 +30,7 @@
  get_project_config,
  get_project_dir,
  parse_config_args,
+ unflatten_dict,
 )
 
 # Mock constants
@@ -229,6 +230,13 @@ def test_flatten_dict() -> None:
  assert flatten_dict(raw_dict) == expected
 
 
+def test_unflatten_dict() -> None:
+ """Test unflatten_dict with a flat dictionary."""
+ raw_dict = {"a.b.c": "d", "e": "f"}
+ expected = {"a": {"b": {"c": "d"}}, "e": "f"}
+ assert unflatten_dict(raw_dict) == expected
+
+
 def test_parse_config_args_none() -> None:
  """Test parse_config_args with None as input."""
  assert not parse_config_args(None)