正则化强度alpha

from sklearn.datasets import load_digits
from sklearn.neural_network import MLPClassifier
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
digits = load_digits()
X = digits.data / 16.0
X_train, X_test, y_train, y_test = train_test_split(X, digits.target, test_size=0.2, random_state=42)
for alpha in [1e-4, 1e-3, 1e-2, 1e-1]:
    clf = MLPClassifier(hidden_layer_sizes=(30,), alpha=alpha, max_iter=500, random_state=42)
    clf.fit(X_train, y_train)
    print(f'alpha={alpha}: {accuracy_score(y_test, clf.predict(X_test)):.4f}')