[python] add type hints to _compare_params_for_warning() and make it reusable

python-package/lightgbm/basic.py

@@ -1756,17 +1756,29 @@ def __init_from_csc(self, csc, params_str, ref_dataset):
  return self
 
  @staticmethod
- def _compare_params_for_warning(params, other_params):
- """Compare params.
+ def _compare_params_for_warning(
+ params: Optional[Dict[str, Any]],
+ other_params: Optional[Dict[str, Any]],
+ ignore_keys: Set[str]
+ ) -> bool:
+ """Compare two dictionaries with params ignoring some keys.
 
- It is only for the warning purpose. Thus some keys are ignored.
+ It is only for the warning purpose.
+
+ Parameters
+ ----------
+ params : dict or None
+ One dictionary with parameters to compare.
+ other_params : dict or None
+ Another dictionary with parameters to compare.
+ ignore_keys : set
+ Keys that should be ignored during comparing two dictionaries.
 
  Returns
  -------
- compare_result: bool
- If they are equal, return True; Otherwise, return False.
+ compare_result : bool
+ Returns whether two dictionaries with params are equal.
  """
- ignore_keys = _ConfigAliases.get("categorical_feature")
  if params is None:
  params = {}
  if other_params is None:
@@ -1794,7 +1806,11 @@ def construct(self):
  reference_params = self.reference.get_params()
  params = self.get_params()
  if params != reference_params:
- if self._compare_params_for_warning(params, reference_params) is False:
+ if not self._compare_params_for_warning(
+ params=params,
+ other_params=reference_params,
+ ignore_keys=_ConfigAliases.get("categorical_feature")
+ ):
  _log_warning('Overriding the parameters from Reference Dataset.')
  self._update_params(reference_params)
  if self.used_indices is None: