Elastic Net

最新推荐文章于 2025-03-29 21:18:18 发布

Ian_Hwang

最新推荐文章于 2025-03-29 21:18:18 发布

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分类专栏： scikit-learn 文章标签： scikit-learn

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本文通过使用弹性网络回归算法对波士顿房价数据集进行预测分析。首先将数据集按比例划分为训练集和测试集，并对数据进行随机化处理。接着采用交叉验证的方式选择最优的超参数alpha和L1比例。最后对测试集进行预测并评估模型的准确性。

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# coding:utf-8
import sklearn.datasets
import sklearn.linear_model
import numpy.random
import numpy.linalg
import matplotlib.pyplot

if __name__ == "__main__":
    # Load boston dataset
    boston = sklearn.datasets.load_boston()

    # Split the dataset with sampleRatio
    sampleRatio = 0.5
    n_samples = len(boston.target)
    sampleBoundary = int(n_samples * sampleRatio)

    # Shuffle the whole data
    shuffleIdx = range(n_samples)
    numpy.random.shuffle(shuffleIdx)

    # Make the training data
    train_features = boston.data[shuffleIdx[:sampleBoundary]]
    train_targets = boston.target[shuffleIdx[:sampleBoundary]]

    # Make the testing data
    test_features = boston.data[shuffleIdx[sampleBoundary:]]
    test_targets = boston.target[shuffleIdx[sampleBoundary:]]

    # Train
    elasticNet = sklearn.linear_model.ElasticNetCV(alphas = [0.01, 0.05, 0.1, 0.5, 1.0, 10.0],
                                                   l1_ratio = [0.1, 0.3, 0.5, 0.7, 0.9])
    elasticNet.fit(train_features, train_targets)
    print("Alpha = ", elasticNet.alpha_)
    print("L1 Ratio = ", elasticNet.l1_ratio_)

    # Predict
    predict_targets = elasticNet.predict(test_features)

    # Evaluation
    n_test_samples = len(test_targets)
    X = range(n_test_samples)
    error = numpy.linalg.norm(predict_targets - test_targets, ord = 1) / n_test_samples
    print("Elastic Net (Boston) Error: %.2f" %(error))

    #Draw
    matplotlib.pyplot.plot(X, predict_targets, 'r--', label = 'Predict Price')
    matplotlib.pyplot.plot(X, test_targets, 'g:', label='True Price')
    legend = matplotlib.pyplot.legend()
    matplotlib.pyplot.title("Elastic Net (Boston)")
    matplotlib.pyplot.ylabel("Price (1000 U.S.D)")
    matplotlib.pyplot.savefig("Elastic Net (Boston).png", format='png')
    matplotlib.pyplot.show()