diff --git a/function.py b/function.py index 61f82d1..7337ce1 100644 --- a/function.py +++ b/function.py @@ -4,60 +4,130 @@ from sklearn.feature_selection import SelectKBest, f_classif # 填写学号和姓名 id = "202210423213" -name = "熊浩燃" +name = " 熊浩燃" def load_data(filepath, k_features=20): - data, labels = [], [] + """ + 从文件中加载数据并进行预处理,包括缺失值填充和特征选择。 + + Args: + - filepath (str): 数据文件路径。 + - k_features (int): 选择的特征数量。 + + Returns: + - np.array: 特征数据。 + - np.array: 标签数据。 + """ + data = [] + labels = [] with open(filepath, 'r') as file: for line in file: line = line.strip().split() if line: - features = [float(feature) if feature.replace('.', '', 1).isdigit() else np.nan for feature in line[:-1]] + features = [] + for feature in line[:-1]: # 最后一个元素是标签 + try: + features.append(float(feature)) + except ValueError: + features.append(np.nan) # 用 NaN 表示缺失值 label = int(line[-1]) data.append(features) labels.append(label) - data, labels = np.array(data), np.array(labels) + # 转换为 numpy 数组 + data = np.array(data) + labels = np.array(labels) + + # 使用SimpleImputer填充NaN imputer = SimpleImputer(strategy='mean') data = imputer.fit_transform(data) - - mean, std_dev = data.mean(axis=0), data.std(axis=0) - std_dev[std_dev == 0] = 1 + + # 特征标准化,避免除零错误 + mean = data.mean(axis=0) + std_dev = data.std(axis=0) + std_dev[std_dev == 0] = 1 # 如果标准差为0,将其设为1,避免除以零 data = (data - mean) / std_dev + # 特征选择 selector = SelectKBest(f_classif, k=k_features) data = selector.fit_transform(data, labels) return data, labels def sigmoid(z): + """ + Sigmoid激活函数,用于对率回归模型。 + + Args: + - z (numpy array): 输入数据。 + + Returns: + - numpy array: Sigmoid函数输出值。 + """ return 1 / (1 + np.exp(-z)) def train_logreg(X, y, initial_lr=0.005, iterations=5000, regularization=0.01, decay=0.0001): + """ + 对率回归训练函数,包含学习率衰减策略。 + + Args: + - X (numpy array): 特征数据。 + - y (numpy array): 标签数据。 + - initial_lr (float): 初始学习率。 + - iterations (int): 迭代次数。 + - regularization (float): 正则化强度。 + - decay (float): 学习率衰减系数。 + + Returns: + - numpy array: 训练得到的权重。 + """ m, n = X.shape weights = np.zeros(n) learning_rate = initial_lr for i in range(iterations): - predictions = sigmoid(np.dot(X, weights)) + z = np.dot(X, weights) + predictions = sigmoid(z) errors = y - predictions - gradient = (np.dot(X.T, errors) - regularization * weights) / m + gradient = np.dot(X.T, errors) / m - regularization * weights / m weights += learning_rate * gradient + + # 学习率衰减 learning_rate = initial_lr / (1 + decay * i) return weights -def predict_logreg(X, weights, threshold=0.5): - probabilities = sigmoid(np.dot(X, weights)) - return (probabilities >= threshold).astype(int) +def predict_logreg(inX, weights, threshold=0.5): + """ + 对率回归预测函数,包含可调阈值。 + + Args: + - inX (numpy array): 输入待分类的样本。 + - weights (numpy array): 训练得到的权重。 + - threshold (float): 判定阈值,默认为0.5。 + + Returns: + - int: 预测的分类标签。 + """ + probability = sigmoid(np.dot(inX, weights)) + return 1 if probability >= threshold else 2 # 测试代码 if __name__ == "__main__": + # 加载数据并选择前20个最重要的特征 X_train, y_train = load_data("./data/horse-colic.data", k_features=20) X_test, y_test = load_data("./data/horse-colic.test", k_features=20) + # 训练模型 weights = train_logreg(X_train, y_train, initial_lr=0.005, iterations=5000, regularization=0.01, decay=0.0001) - y_pred = predict_logreg(X_test, weights, threshold=0.5) - accuracy = np.mean(y_pred == y_test) - print(f"测试集准确率: {accuracy:.2f}") + # 模型评估 + correct_predictions = 0 + for i in range(len(X_test)): + y_pred = predict_logreg(X_test[i], weights, threshold=0.5) + if y_pred == y_test[i]: + correct_predictions += 1 + print(f"预测结果: {y_pred}, 实际结果: {y_test[i]}") + + accuracy = correct_predictions / len(X_test) + print(f"测试集准确率: {accuracy:.2f}") \ No newline at end of file