diff --git a/function.py b/function.py index 1e2aaa4..2641e0b 100644 --- a/function.py +++ b/function.py @@ -6,7 +6,7 @@ import time id = "202210423220" name = "方子涵" -def classify(input_vector, dataSet, labels, k=5): +def classify(input_vector, dataSet, labels, k=3): """ KNN 分类算法。 @@ -14,7 +14,7 @@ def classify(input_vector, dataSet, labels, k=5): - input_vector (numpy array): 输入待分类的样本。 - dataSet (numpy array): 训练数据集。 - labels (list or numpy array): 训练集对应的标签。 - - k (int): kNN 算法参数,默认值为 5。 + - k (int): kNN 算法参数,默认值为 3。 Returns: - int: 预测的分类标签。 @@ -27,10 +27,17 @@ def classify(input_vector, dataSet, labels, k=5): # 获取距离最近的 k 个样本的索引 sortedDistIndices = distances.argsort() classCount = {} + weightSum = {} + # 使用加权多数表决法 for i in range(k): voteIlabel = labels[sortedDistIndices[i]] - # 统计每个类别的出现次数 - classCount[voteIlabel] = classCount.get(voteIlabel, 0) + 1 + # 统计每个类别的出现次数,并使用距离的倒数作为权重 + weight = 1 / (distances[sortedDistIndices[i]] + 1e-5) # 加上一个小常数防止除以零 + classCount[voteIlabel] = classCount.get(voteIlabel, 0) + weight + weightSum[voteIlabel] = weightSum.get(voteIlabel, 0) + 1 + # 计算加权平均值 + for className in classCount: + classCount[className] /= weightSum[className] # 返回出现次数最多的类别 sortedClassCount = sorted(classCount.items(), key=lambda x: x[1], reverse=True) return sortedClassCount[0][0] @@ -127,8 +134,10 @@ if __name__ == "__main__": ) test_data_vector = np.array([int(char) for char in test_data]).reshape(1, 1024) - # 使用k=5进行分类 - start_time = time.time() - predicted_label = classify(test_data_vector, train_data, train_labels, k=5) - end_time = time.time() - print(f"k = 5, 预测的标签: {predicted_label}, 执行时间: {end_time - start_time:.2f} 秒") \ No newline at end of file + # 测试不同的k值 + k_values = [1, 3, 5, 7, 9] + for k in k_values: + start_time = time.time() + predicted_label = classify(test_data_vector, train_data, train_labels, k) + end_time = time.time() + print(f"k = {k}, 预测的标签: {predicted_label}, 执行时间: {end_time - start_time:.2f} 秒") \ No newline at end of file