diff --git a/function.py b/function.py index 86185fd..39fc267 100644 --- a/function.py +++ b/function.py @@ -41,10 +41,42 @@ name = "章程鸿" # 这里写自己的代码实现 import numpy as np +from collections import Counter from sklearn.model_selection import GridSearchCV from sklearn.neighbors import KNeighborsClassifier -from sklearn.preprocessing import MinMaxScaler -from sklearn.metrics import accuracy_score + +def classify0(inX, dataSet, labels, k=1): + """ + KNN 分类算法。 + + Args: + - inX (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,默认为3。 + + Returns: + - int: 预测的分类标签。 + """ + # 计算马氏距离 + cov_matrix = np.cov(dataSet, rowvar=False) + inv_cov_matrix = np.linalg.inv(cov_matrix) + mean_vector = np.mean(dataSet, axis=0) + + diffMat = inX - dataSet + mahalanobis_distances = np.sqrt(np.sum((diffMat @ inv_cov_matrix) * diffMat, axis=1)) + + # 排序并选取前k个最小距离 + sortedDistIndices = mahalanobis_distances.argsort() + classCount = {} + + for i in range(k): + voteIlabel = labels[sortedDistIndices[i]] + classCount[voteIlabel] = classCount.get(voteIlabel, 0) + 1 + + # 返回出现频率最高的类别 + sortedClassCount = sorted(classCount.items(), key=lambda x: x[1], reverse=True) + return sortedClassCount[0][0] def load_data(file_path): """ @@ -55,18 +87,36 @@ def load_data(file_path): labels = data[:, -1].astype(int) return features, labels -if __name__ == "__main__": - train_file = "datingTrainSet2.tsv" - test_file = "datingTestSet2.tsv" # 假设您有一个测试集文件 - - # 加载训练和测试数据 - train_data, train_labels = load_data(train_file) - test_data, test_labels = load_data(test_file) +def normalize_min_max(data): + """ + 对数据进行最小-最大缩放归一化。 - # 使用MinMaxScaler进行归一化 - scaler = MinMaxScaler() - train_data_normalized = scaler.fit_transform(train_data) - test_data_normalized = scaler.transform(test_data) + Args: + - data (numpy array): 待归一化的数据。 + + Returns: + - numpy array: 归一化后的数据。 + - numpy array: 最小值。 + - numpy array: 最大值。 + """ + min_vals = data.min(0) + max_vals = data.max(0) + ranges = max_vals - min_vals + # 避免除以零的情况 + ranges[ranges == 0.0] = 1.0 + m = data.shape[0] + norm_data = (data - min_vals) / ranges + return norm_data, min_vals, max_vals + +if __name__ == "__main__": + # 以下代码可用于测试,可自行随意修改 + train_file = "datingTrainSet2.tsv" + + # 加载训练数据 + train_data, train_labels = load_data(train_file) + + # 归一化训练数据,并获取最小值和最大值 + train_data_normalized, min_vals, max_vals = normalize_min_max(train_data) # 定义KNN分类器 knn = KNeighborsClassifier() @@ -86,14 +136,10 @@ if __name__ == "__main__": best_knn = KNeighborsClassifier(n_neighbors=optimal_k) best_knn.fit(train_data_normalized, train_labels) - # 对测试数据进行预测 - predicted_labels = best_knn.predict(test_data_normalized) + # 测试数据点也需要用同样的方式归一化 + test_point = np.array([65915, 3.868359, 0.128078]) + test_point_normalized = (test_point - min_vals) / (max_vals - min_vals) - # 输出预测结果 - print("预测的分类标签是:") - for i, (predicted, actual) in enumerate(zip(predicted_labels, test_labels)): - print(f"样本 {i+1}: 预测标签: {predicted}, 实际标签: {actual}") - - # 计算并输出准确率 - accuracy = accuracy_score(test_labels, predicted_labels) - print(f"模型在测试集上的准确率为: {accuracy * 100:.2f}%") \ No newline at end of file + # 使用归一化后的数据进行预测 + predicted_label = best_knn.predict([test_point_normalized]) + print("预测的分类标签是:", predicted_label[0])