岭回归

def solve():
    from sklearn.datasets import load_diabetes
    from sklearn.linear_model import Ridge, LinearRegression
    from sklearn.model_selection import train_test_split
    from sklearn.metrics import r2_score
    import matplotlib.pyplot as plt
    import numpy as np
    diabetes = load_diabetes()
    X_train, X_test, y_train, y_test = train_test_split(____)
    alphas = [____, ____, ____, ____, ____]
    r2_scores = []
    for alpha in alphas:
        ridge = Ridge(____)
        ridge.fit(____)
        y_pred = ridge.predict(____)
        r2_scores.append(r2_score(____))
    print(____)
    for a, r2 in zip(____):
        print(____)
    plt.figure(figsize=(____, ____))
    plt.semilogx(____)
    plt.xlabel(____)
    plt.ylabel(____)
    plt.title(____)
    plt.grid(____)
    plt.show()