from sklearn.experimental import enable_halving_search_cv # noqa
from sklearn.model_selection import HalvingRandomSearchCV, RandomizedSearchCV

from sklearn.tree import DecisionTreeClassifier
from sklearn.linear_model import LogisticRegression
from sklearn.pipeline import Pipeline
from sklearn.datasets import load_iris

X, y = load_iris(return_X_y=True)

pipe = Pipeline([("clf", None)])
params = [
    {'clf': (DecisionTreeClassifier(),), 'clf__criterion': ['entropy', 'gini']},
    {'clf': (LogisticRegression(),), 'clf__C': [0.01, 0.1, 1, 10, 100], 'clf__max_iter': [10_000]}
]

search = HalvingRandomSearchCV(
    pipe, param_distributions=params, scoring="accuracy")

search.fit(X, y)

---------------------------------------------------------------------------
InvalidParameterError                     Traceback (most recent call last)
Cell In[22], line 20
     12 params = [
     13     {'clf': (DecisionTreeClassifier(),), 'clf__criterion': ['entropy', 'gini']},
     14     {'clf': (LogisticRegression(),), 'clf__C': [0.01, 0.1, 1, 10, 100], 'clf__max_iter': [10_000]}
     15 ]
     17 search = HalvingRandomSearchCV(
     18     pipe, param_distributions=params, scoring="accuracy")
---> 20 search.fit(X, y)

File ~\AppData\Local\miniconda3\envs\automl\lib\site-packages\sklearn\base.py:1144, in _fit_context.<locals>.decorator.<locals>.wrapper(estimator, *args, **kwargs)
   1139 partial_fit_and_fitted = (
   1140     fit_method.__name__ == "partial_fit" and _is_fitted(estimator)
   1141 )
   1143 if not global_skip_validation and not partial_fit_and_fitted:
-> 1144     estimator._validate_params()
   1146 with config_context(
   1147     skip_parameter_validation=(
   1148         prefer_skip_nested_validation or global_skip_validation
   1149     )
   1150 ):
   1151     return fit_method(estimator, *args, **kwargs)

File ~\AppData\Local\miniconda3\envs\automl\lib\site-packages\sklearn\base.py:637, in BaseEstimator._validate_params(self)
    629 def _validate_params(self):
    630     """Validate types and values of constructor parameters
    631 
    632     The expected type and values must be defined in the `_parameter_constraints`
   (...)
    635     accepted constraints.
    636     """
--> 637     validate_parameter_constraints(
    638         self._parameter_constraints,
    639         self.get_params(deep=False),
    640         caller_name=self.__class__.__name__,
    641     )

File ~\AppData\Local\miniconda3\envs\automl\lib\site-packages\sklearn\utils\_param_validation.py:95, in validate_parameter_constraints(parameter_constraints, params, caller_name)
     89 else:
     90     constraints_str = (
     91         f"{', '.join([str(c) for c in constraints[:-1]])} or"
     92         f" {constraints[-1]}"
     93     )
---> 95 raise InvalidParameterError(
     96     f"The {param_name!r} parameter of {caller_name} must be"
     97     f" {constraints_str}. Got {param_val!r} instead."
     98 )

InvalidParameterError: The 'param_distributions' parameter of HalvingRandomSearchCV must be an instance of 'dict'. Got [{'clf': (DecisionTreeClassifier(),), 'clf__criterion': ['entropy', 'gini']}, {'clf': (LogisticRegression(),), 'clf__C': [0.01, 0.1, 1, 10, 100], 'clf__max_iter': [10000]}] instead.