diff --git a/function.py b/function.py index 02b691a..ba8d467 100644 --- a/function.py +++ b/function.py @@ -35,20 +35,26 @@ def load_data(filepath): y = data[:, -1] return X, y -def train_logreg(X, y, learning_rate=0.01, iterations=1000): - """训练逻辑回归模型,使用随机梯度下降.""" +def train_logreg(X, y, initial_learning_rate=0.1, iterations=1000, decay_rate=0.01): + """训练逻辑回归模型,使用随机梯度下降和学习率衰减.""" n_samples, n_features = X.shape weights = np.zeros(n_features + 1) # 增加一位用于偏置 X = np.c_[X, np.ones((n_samples, 1))] # 增加偏置项 - for _ in range(iterations): + for i in range(iterations): + # 更新学习率 + learning_rate = initial_learning_rate / (1 + decay_rate * i) + random_index = np.random.randint(n_samples) X_i = X[random_index] y_i = y[random_index] linear_model = np.dot(X_i, weights) - dw = (linear_model - y_i) * X_i - weights -= learning_rate * dw + prediction = 1 / (1 + np.exp(-linear_model)) # Sigmoid函数 + error = prediction - y_i + + # 更新权重 + weights -= learning_rate * error * X_i return weights @@ -56,7 +62,8 @@ def predict_logreg(inX, weights): """使用线性模型预测结果.""" inX = np.append(inX, 1) # 增加偏置项 linear_model = np.dot(inX, weights) - return 1.0 if linear_model >= 0 else 2.0 + prediction = 1 / (1 + np.exp(-linear_model)) + return 1.0 if prediction >= 0.5 else 2.0 # 返回1.0或2.0 if __name__ == "__main__": # 加载训练集