generated from LufsX/Experiment-kNN
147 lines
4.7 KiB
Python
147 lines
4.7 KiB
Python
import numpy as np
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import os
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"""
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实验说明:
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- 自行编写实现数据加载与 kNN 的手写数字分类算法。
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- 函数输入: 待分类的样本 input_vector, 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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- 在 function.py 中实现 kNN 分类算法。
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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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- 自动评测脚本仅会加载 classify 和 load_data 函数，请勿修改函数名。
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- 训练集和测试集需手动下载解压，并放入当前目录下。
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测评环境:
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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 = "202210423203"
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name = "赵昊龙"
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def classify(input_vector, 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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- input_vector (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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# 欧式距离
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diffMat = np.tile(input_vector, (dataSet.shape[0], 1)) - dataSet
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sqDiffMat = diffMat**2
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sqDistances = sqDiffMat.sum(axis=1)
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distances = sqDistances**0.5
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sortedDistIndices = distances.argsort()
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# 取出距离最近的k个点的标签
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classCount = {}
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for i in range(k):
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voteIlabel = labels[sortedDistIndices[i]]
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# 统计每个类别的出现次数
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classCount[voteIlabel] = classCount.get(voteIlabel, 0) + 1
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# 选择出现次数最多的类别作为预测标签
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sortedClassCount = sorted(classCount.items(), key=lambda x: x[1], reverse=True)
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return sortedClassCount[0][0]
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def load_dataset(directory):
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"""
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从文件夹中加载数据。
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Args:
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- directory (str): 数据文件夹路径。
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Returns:
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- np.array: 特征数据。
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- np.array: 标签数据。
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"""
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fileList = os.listdir(directory)
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m = len(fileList)
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dataSet = np.zeros((m, 1024)) # 28*28的二值图像数据
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labels = []
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for i in range(m):
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filename = fileList[i]
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fileWithPath = os.path.join(directory, filename)
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vector = img_to_vector(fileWithPath)
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dataSet[i, :] = vector
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label = int(filename.split('.')[0]) # 假设文件名的格式为"数字.txt"
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labels.append(label)
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return dataSet, np.array(labels)
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def img_to_vector(filename):
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"""
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将二值图像转换为向量。
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Args:
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- filename (str): 图像文件路径。
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Returns:
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- np.array: 二值图像向量。
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"""
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returnVect = np.zeros((1024,)) # 28*28的二值图像数据
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with open(filename, 'r') as file:
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lines = file.readlines()
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n = 0
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for line in lines:
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for i in range(len(line)-1):
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returnVect[n] = int(line[i])
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n = n + 1
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return returnVect
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if __name__ == "__main__":
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train_data, train_labels = load_dataset("trainingDigits")
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test_data = (
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"00000000000000110000000000000000"
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"00000000000011111000000000000000"
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"00000000000011111100000000000000"
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"00000000001111111110000000000000"
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"00000000001111111110000000000000"
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"00000000001111111100000000000000"
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"00000000011111111000000000000000"
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"00000000111111111000000000000000"
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"00000000111111110000000000000000"
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"00000000111111110000000000000000"
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"00000000111111110000000000000000"
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"00000000111111110000000000000000"
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"00000000111111100000000000000000"
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"00000001111111100000000000000000"
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"00000001111111100000000000000000"
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"00000001111111100000000000000000"
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"00000001111111111111000000000000"
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"00000001111111111111111000000000"
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"00000001111111111111111100000000"
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"00000011111111111111111110000000"
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"00000011111111111111111110000000"
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"00000001111111111111111110000000"
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"00000001111111111111111110000000"
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"00000000111111111100111111100000"
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"00000000111111111000111111100000"
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"00000000011111111001111111100000"
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"00000000011111111111111111000000"
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"00000000001111111111111111000000"
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"00000000000111111111111111000000"
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"00000000000011111111111100000000"
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"00000000000001111111110000000000"
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"00000000000000000111100000000000"
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)
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predicted_label = classify(
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np.array([int(char) for char in test_data]).reshape(1, 1024),
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train_data,
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train_labels,
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)
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print(f"预测的标签: {predicted_label}") |