diff --git a/function.py b/function.py index e147db3..532a67b 100644 --- a/function.py +++ b/function.py @@ -3,7 +3,6 @@ import numpy as np from collections import Counter from scipy.spatial import distance - """ 挑战说明: - 自行编写实现 KNN 分类算法。 @@ -41,7 +40,7 @@ name = "程悦" # 这里写自己的代码实现 -def classify0(inX, dataSet, labels, inv_cov_matrix, k=9): +def classify0(inX, dataSet, labels, k=9): """ KNN 分类算法。 @@ -54,19 +53,25 @@ def classify0(inX, dataSet, labels, inv_cov_matrix, k=9): Returns: - int: 预测的分类标签。 """ + # 计算协方差矩阵并求逆矩阵 + cov_matrix = np.cov(dataSet, rowvar=False) + inv_cov_matrix = np.linalg.inv(cov_matrix) + # 计算输入样本与训练集样本的马氏距离 - distances = distance.cdist(dataSet, np.array([inX]), 'mahalanobis', VI=inv_cov_matrix).flatten() + distances = [distance.mahalanobis(inX, data_point, inv_cov_matrix) for data_point in dataSet] # 按距离排序并选择前 k 个最近的邻居 - k_indices = np.argpartition(distances, k)[:k] - k_nearest_labels = labels[k_indices] + k_indices = np.argsort(distances)[:k] + k_nearest_labels = [labels[i] for i in k_indices] # 统计最近邻居中最多的标签 - most_common_label = Counter(k_nearest_labels).most_common(1)[0][0] + label_counts = Counter(k_nearest_labels) + most_common_label = label_counts.most_common(1)[0][0] return most_common_label + def load_data(file_path): """ 加载 TSV 格式数据文件。 @@ -83,20 +88,17 @@ if __name__ == "__main__": train_data, train_labels = load_data(train_file) test_data, test_labels = load_data(test_file) - # 计算协方差矩阵并求逆矩阵 - cov_matrix = np.cov(train_data, rowvar=False) - inv_cov_matrix = np.linalg.inv(cov_matrix) - # 测试 classify0 函数 test_sample = test_data[0] # 使用测试集中的第一个样本进行测试 - predicted_label = classify0(test_sample, train_data, train_labels, inv_cov_matrix) + predicted_label = classify0(test_sample, train_data, train_labels) print(f"Predicted label: {predicted_label}, Actual label: {test_labels[0]}") # 遍历整个测试集来评估分类器的性能 - correct_count = sum( - classify0(test_data[i], train_data, train_labels, inv_cov_matrix) == test_labels[i] - for i in range(len(test_data)) - ) + correct_count = 0 + for i in range(len(test_data)): + predicted_label = classify0(test_data[i], train_data, train_labels) + if predicted_label == test_labels[i]: + correct_count += 1 accuracy = correct_count / len(test_data) print(f"Accuracy: {accuracy * 100:.2f}%")