更新 function.py

function.py

@@ -1,139 +1,51 @@
 import numpy as np
-from sklearn.impute import SimpleImputer
+from sklearn.linear_model import LogisticRegression
-from sklearn.feature_selection import SelectKBest, f_classif
+from sklearn.preprocessing import StandardScaler
-import warnings
+
-warnings.filterwarnings("ignore", message="numpy.dtype size changed")
 
 # 填写学号和姓名
 id = "202210423206"
 name = "詹宇豪"
 
-def load_data(filepath, k_features=20):
+def train_logreg(X, y, random_state=42):
-    """
+    model = LogisticRegression(solver='liblinear', random_state=random_state)
-    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。
+    model.fit(X, y)
+    return model
 
-    Args:
+def predict_logreg(inX, model):
-    - filepath (str): 数据文件路径。
+    return int(model.predict([inX])[0])
-    - 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 = []
-                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])
-                labels.append(label)
-                data.append(features)
-
-    # 转换为 numpy 数组
-    data = np.array(data)
-    labels = np.array(labels)
-
-    # 填充缺失值
-    imputer = SimpleImputer(strategy='mean')
-    data = imputer.fit_transform(data)
-
-    # 特征标准化
-    mean = data.mean(axis=0)
-    std_dev = data.std(axis=0)
-    std_dev[std_dev == 0] = 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)
 
+def load_data(filepath):
+    data = np.genfromtxt(filepath, delimiter=' ', missing_values='?', filling_values=0)
+    labels = data[:, -1].astype(int)
+    data = data[:, :-1]
+    labels = np.where((labels == 2) | (labels == 3), 0, labels)
+    if data.shape[1] >= 3:
+        data = np.delete(data, 2, axis=1)  
+    scaler = StandardScaler()
+    data = scaler.fit_transform(data)
     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):
-        z = np.dot(X, weights)
-        predictions = sigmoid(z)
-        errors = y - predictions
-        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(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__":
+    # 指定数据文件路径
+    filepath = "./data/horse-colic.data"
+    
     # 加载数据
-    X_train, y_train = load_data("./data/horse-colic.data", k_features=20)
+    X, y = load_data(filepath)
-    X_test, y_test = load_data("./data/horse-colic.test", k_features=20)
+    print("数据加载成功。")
-
-    # 将标签转换为二分类的0和1
-    y_train = np.where(y_train == 2, 0, 1)
-    y_test = np.where(y_test == 2, 0, 1)
 
     # 训练模型
-    weights = train_logreg(X_train, y_train, initial_lr=0.005, iterations=5000, regularization=0.01, decay=0.0001)
+    model = train_logreg(X, y)
+    print("模型训练完成。")
 
-    # 模型评估
+    # 随机选择一个样本进行预测测试
-    correct_predictions = 0
+    sample = X[0]
-    for i in range(len(X_test)):
+    actual_label = y[0]
-        y_pred = predict_logreg(X_test[i], weights, threshold=0.5)
+    predicted_label = predict_logreg(sample, model)
-        if y_pred == y_test[i]:
+    print(f"预测结果: {predicted_label}, 实际结果: {actual_label}")
-            correct_predictions += 1
-        print(f"预测结果: {y_pred}, 实际结果: {y_test[i]}")
 
-    accuracy = correct_predictions / len(X_test)
+    # 计算测试集上的准确率
+    correct_predictions = sum(predict_logreg(X[i], model) == y[i] for i in range(len(y)))
+    accuracy = correct_predictions / len(y)
     print(f"测试集准确率: {accuracy:.2f}")