generated from LufsX/Experiment-LogReg
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import os
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import numpy as np
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"""
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实验说明:
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- 自行编写实现数据加载与预测病马死亡的对率回归算法。
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注意事项:
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- 在 function.py 中实现对率回归算法。
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- 可以自行导入其他库，需要在 requirements.txt 添加依赖，若未在 requirements.txt 中添加使用到的依赖，则无法自动评测，成绩为零。
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- 自动评测脚本仅会加载 train_logreg、predict_logreg 和 load_data 函数，请勿修改函数名。
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测评环境:
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- CPU: Intel Xeon(R) CPU E3-1231 v3 @ 3.40GHz
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- OS: Ubuntu 22.04.4 LTS
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- Python: 3.10.12
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- numpy: 2.1.1
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"""
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"""
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请在这里填写学号和姓名，不填写即成绩无效。
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"""
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id = "202210423105"
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name = "魏明帅"
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# 这里写自己的代码实现
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import numpy as np
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from sklearn.preprocessing import MinMaxScaler
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from sklearn.model_selection import train_test_split
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def sigmoid(z):
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return 1.0 / (1 + np.exp(-z))
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def compute_gradient(X_batch, y_batch, weights, lambda_reg):
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z = np.dot(X_batch, weights)
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h = sigmoid(z)
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gradient = np.dot(X_batch.T, (h - y_batch)) / len(y_batch)
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gradient += (lambda_reg / len(y_batch)) * weights # L2正则化
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return gradient
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def train_logreg(X, y, learning_rate=0.001, iterations=10000, batch_size=64, lambda_reg=0.1):
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def train_logreg(X, y, learning_rate=0.01, iterations=1000):
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m, n = X.shape
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weights = np.random.randn(n) * np.sqrt(2. / n) # He初始化
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best_weights = weights.copy()
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best_accuracy = 0
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# 添加偏置项
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X = np.c_[np.ones((m, 1)), X]
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weights = np.zeros(n + 1)
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for _ in range(iterations):
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indices = np.random.permutation(m)
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X_shuffled = X[indices]
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y_shuffled = y[indices]
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for j in range(0, m, batch_size):
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X_batch = X_shuffled[j:j + batch_size]
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y_batch = y_shuffled[j:j + batch_size]
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gradient = compute_gradient(X_batch, y_batch, weights, lambda_reg)
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weights -= learning_rate * gradient
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# 计算训练集准确率
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train_accuracy = accuracy(X, y, weights)
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if train_accuracy > best_accuracy:
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best_accuracy = train_accuracy
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best_weights = weights.copy()
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# 动态调整学习率
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if _ % 100 == 0 and train_accuracy > 0.95: # 达到高准确率时减小学习率
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learning_rate *= 0.9
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return best_weights
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def predict_logreg(X, weights):
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z = np.dot(X, weights)
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h = sigmoid(z)
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return np.where(h >= 0.5, 1, 0)
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for i in range(m):
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x_i = X[i]
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y_i = y[i]
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z = np.dot(x_i, weights)
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h = 1 / (1 + np.exp(-z))
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error = y_i - h
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weights += learning_rate * error * x_i
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return weights
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def predict_logreg(inX, weights):
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z = np.dot(inX, weights)
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h = 1 / (1 + np.exp(-z))
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return 1 if h >= 0.5 else 0
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def load_data(filepath):
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data, labels = [], []
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X = []
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y = []
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with open(filepath, 'r') as f:
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for line in f:
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line = line.strip().split()
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if len(line) >= 1 and line[-1].isdigit():
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line_data = [0 if x == '?' else float(x) for x in line[:-1]]
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data.append(line_data)
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labels.append(int(line[-1]))
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data = np.array(data)
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labels = np.array(labels)
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values = line.strip().split()
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# 跳过包含 '?' 的行
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if '?' in values:
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continue
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# 将标签和特征转换为浮点数
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y.append(float(values[-1]))
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X.append([float(x) for x in values[:-1]])
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num_features = data.shape[1]
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X_array = np.array(X)
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y_array = np.array(y).reshape(-1, 1)
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indices_to_delete = [2]
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if num_features > 24:
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indices_to_delete += list(range(24, 27))
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# 特征缩放，处理标准差为零的特征
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means = np.mean(X_array, axis=0)
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stds = np.std(X_array, axis=0)
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X_scaled = (X_array - means) / np.where(stds == 0, 1, stds)
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data = np.delete(data, indices_to_delete, axis=1)
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target_variable = np.where((labels == 2) | (labels == 3), 0, 1)
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return data, target_variable
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def accuracy(X, y, weights):
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predictions = predict_logreg(X, weights)
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return np.mean(predictions == y)
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return X_scaled, y_array
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if __name__ == "__main__":
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# 加载数据
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X, y = load_data("./data/horse-colic.data")
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# 拆分训练集和验证集
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X_train, X_val, y_train, y_val = train_test_split(X, y, test_size=0.2, random_state=42)
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# 数据归一化
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scaler = MinMaxScaler()
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X_train = scaler.fit_transform(X_train)
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X_val = scaler.transform(X_val)
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# 训练模型
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final_weights = train_logreg(X_train, y_train, learning_rate=0.01, iterations=5000, batch_size=64, lambda_reg=0.1)
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# 验证模型
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val_accuracy = accuracy(X_val, y_val, final_weights)
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print(f"验证集的准确率: {val_accuracy:.4f}")
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# 加载测试集
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X_train, y_train = load_data("./data/horse-colic.data")
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X_test, y_test = load_data("./data/horse-colic.test")
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X_test = scaler.transform(X_test)
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# 测试模型
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final_test_accuracy = accuracy(X_test, y_test, final_weights)
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print(f"最终测试集的准确率: {final_test_accuracy:.4f}")
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weights = train_logreg(X_train, y_train, learning_rate=0.01, iterations=1000)
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y_pred = predict_logreg(X_test[11], weights)
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print(f"预测结果: {y_pred}, 实际结果: {y_test[11]}")
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