sample_weights.py

from typing import Union

import numpy as np
import pandas as pd

def create_sample_weights(
    y_train: np.ndarray, 
    X_train: Union[np.ndarray, pd.DataFrame]
) -> pd.Series:
    y_series = pd.DataFrame({"y": y_train})["y"]
    class_weights = len(X_train) / y_series.value_counts()
    sample_weights = y_series.map(class_weights)
    return sample_weights
  
"""Example:

>>> sample_weights = create_sample_weights(y_train, X_train)
>>> model = HistGradientBoostingClassifier(**params)
>>> model.fit(X_train, y_train, sample_weight=sample_weights)
"""