generated from LufsX/Challenge-kNN
120 lines
3.4 KiB
Python
120 lines
3.4 KiB
Python
# function.py
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import numpy as np
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"""
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挑战说明:
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- 自行编写实现 KNN 分类算法。
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- 函数输入: 待分类的样本 inX, 训练数据集 dataSet, 训练集对应的标签 labels。
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- 函数返回: 预测的分类标签。
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注意事项:
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- 可以自行导入其他库，需要在 requirements.txt 添加依赖，若未在 requirements.txt 中添加使用到的依赖，则无法自动评测，成绩为零。
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- 在 function.py 中实现 KNN 分类算法。
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- 自动评测脚本仅会加载 classify0 函数，请勿修改函数名。
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- 训练集在本目录下的 datingTrainSet2.tsv 中。
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- 评测数据集在本目录下的 datingTestSet2.tsv 中。
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挑战环境:
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- CPU: Intel Xeon(R) CPU E3-1231 v3 @ 3.40GHz
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- OS: Ubuntu 22.04.4 LTS
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- Python: 3.10.12
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- numpy: 2.1.1
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"""
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"""
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请在这里填写学号和姓名，不填写即成绩无效。
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"""
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id = "202210423109"
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name = "孔祥芷"
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"""
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参数说明:
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- inX (numpy array): 输入待分类的样本。
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- dataSet (numpy array): 训练数据集。
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- labels (list or numpy array): 训练集对应的标签。
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返回值:
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- int: 预测的分类标签。
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"""
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# 这里写自己的代码实现
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def load_data(file_path):
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"""
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加载 TSV 格式数据文件。
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Args:
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- file_path (str): 文件路径。
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Returns:
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- features (numpy array): 特征数据。
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- labels (numpy array): 标签数据。
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"""
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data = np.loadtxt(file_path, delimiter="\t")
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features = data[:, :-1]
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labels = data[:, -1].astype(int)
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return features, labels
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def classify0(inX, dataSet, labels, k=3):
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"""
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KNN 分类算法。
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Args:
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- inX (numpy array): 输入待分类的样本。
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- dataSet (numpy array): 训练数据集。
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- labels (list or numpy array): 训练集对应的标签。
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- k (int): KNN 算法参数。
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Returns:
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- int: 预测的分类标签。
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"""
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dists = np.sum(np.abs(dataSet - inX), axis=1)
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sorted_index = np.argsort(dists)
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class_count = {}
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for i in range(k):
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vote_label = labels[sorted_index[i]]
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class_count[vote_label] = class_count.get(vote_label, 0) + 1
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sorted_class_count = sorted(class_count.items(), key=lambda item: item[1], reverse=True)
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if sorted_class_count:
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return sorted_class_count[0][0]
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else:
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return -1
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def normalize(features):
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min_vals = features.min(axis=0)
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max_vals = features.max(axis=0)
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ranges = max_vals - min_vals
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normalized = (features - min_vals) / ranges
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normalized[ranges == 0] = 0 # 防止除以零
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return normalized
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if __name__ == "__main__":
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train_features, train_labels = load_data("datingTrainSet2.tsv")
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test_features, test_labels = load_data("datingTestSet2.tsv")
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train_features = normalize(train_features)
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test_features = normalize(test_features)
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best_k = 3
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best_accuracy = 0.0
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for k in range(1, 10): # 尝试不同的 K 值
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correct_count = 0
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for i in range(len(test_features)):
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test_feature = test_features[i].reshape(1, -1)
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predict_label = classify0(test_feature, train_features, train_labels, k=k)
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if predict_label == -1:
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continue
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correct_count += (predict_label == test_labels[i])
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accuracy = correct_count / len(test_features)
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print(f"Accuracy with k={k}: {accuracy:.2f}")
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if accuracy > best_accuracy:
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best_accuracy = accuracy
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best_k = k
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print(f"Best K: {best_k}, Best Accuracy: {best_accuracy:.2f}") |