knn.minist_recognition/FullTest(1).cpp

#include <algorithm>
#include <cmath>
#include <iostream>
#include <unordered_map>
#include <vector>
#include <fstream>
#include <sstream>
#include <filesystem>

// 定义图像类
class Image {
private:
    std::vector<std::vector<int>> pixels; // 像素数组
    int width; // 图像宽度
    int height; // 图像高度

public:
    Image(std::vector<std::vector<int>> pixels, int width, int height) : pixels(pixels), width(width), height(height) {}

    // 获取像素值
    int getPixelValue(int x, int y) const {
        return pixels[x][y];
    }

    // 获取图像宽度
    int getWidth() const {
        return width;
    }

    // 获取图像高度
    int getHeight() const {
        return height;
    }
};

class ImageProcessor {
public:
    // 加载图像并进行预处理
    Image preprocessImage(const std::string& imagePath) {
        return loadTXT(imagePath);
    }

private:
    // 加载TXT图像
    Image loadTXT(const std::string& imagePath) {
        std::ifstream file(imagePath);
        if (!file.is_open()) {
            throw std::runtime_error("Failed to open TXT image file: " + imagePath);
        }

        std::vector<std::vector<int>> pixels;
        std::string line;
        int width = 0;
        while (std::getline(file, line)) {
            std::istringstream iss(line);
            std::vector<int> row;
            int value;
            while (iss >> value) {
                row.push_back(value);
            }
            pixels.push_back(row);
            if (width == 0) {
                width = row.size();
            }
            else if (row.size() != width) {
                throw std::runtime_error("Invalid TXT image format: inconsistent row lengths");
            }
        }

        // Create and return Image object
        return Image(pixels, width, pixels.size());
    }
};

// 特征类
class Feature {
private:
    std::vector<double> values; // 特征值

public:
    Feature(std::vector<double> values) : values(values) {}

    // 获取特征值
    double getValue(int index) const {
        return values[index];
    }

    // 获取特征值数量
    size_t getSize() const {
        return values.size();
    }
};

// 特征提取器
class FeatureExtractor {
public:
    // 从图像中提取特征
    Feature extractFeature(const Image& image) {
        std::vector<double> features;
        for (int y = 0; y < image.getHeight(); ++y) {
            for (int x = 0; x < image.getWidth(); ++x) {
                features.push_back(static_cast<double>(image.getPixelValue(x, y)));
            }
        }
        return Feature(features);
    }
};

// 距离度量类
class DistanceMetric {
public:
    // 计算两个特征之间的距离（欧氏距离）
    double calculateDistance(const Feature& feature1, const Feature& feature2) const {
        if (feature1.getSize() != feature2.getSize()) {
            throw std::runtime_error("Feature vectors must be of the same size");
        }
        double distance = 0.0;
        for (size_t i = 0; i < feature1.getSize(); ++i) {
            distance += pow(feature1.getValue(i) - feature2.getValue(i), 2);
        }
        return sqrt(distance);
    }
};

// KNN 模型
class KNNModel {
private:
    std::vector<Feature> features; // 特征向量
    std::vector<int> labels; // 标签
    DistanceMetric distanceMetric; // 距离度量

public:
    // 训练 KNN 模型
    void train(const std::vector<Feature>& features, const std::vector<int>& labels) {
        this->features = features;
        this->labels = labels;
    }

    // 使用 KNN 模型进行预测
    int predict(const Feature& feature, int k) {
        // 计算待预测特征与训练集中所有特征的距离，并记录索引
        std::vector<std::pair<double, int>> distances;
        for (size_t i = 0; i < features.size(); ++i) {
            double distance = distanceMetric.calculateDistance(features[i], feature);
            distances.push_back(std::make_pair(distance, i));
        }

        // 根据距离排序，选择最近的 K 个样本
        std::sort(distances.begin(), distances.end());

        // 统计最近的 K 个样本中各类别出现的次数
        std::unordered_map<int, int> classCount;
        for (int i = 0; i < k; ++i) {
            int index = distances[i].second;
            int label = labels[index];
            classCount[label]++;
        }

        // 找出最频繁出现的类别
        int maxCount = 0;
        int predictedLabel = -1;
        for (auto& pair : classCount) {
            if (pair.second > maxCount) {
                maxCount = pair.second;
                predictedLabel = pair.first;
            }
        }

        return predictedLabel;
    }
};

// 数字识别器
class DigitRecognizer {
private:
    ImageProcessor imageProcessor;
    FeatureExtractor featureExtractor;
    KNNModel knnModel;

public:
    // 构造函数
    DigitRecognizer(const std::vector<Feature>& trainingFeatures, const std::vector<int>& trainingLabels) {
        knnModel.train(trainingFeatures, trainingLabels);
    }

    // 执行数字识别
    int recognizeDigit(const std::string& imagePath) {
        // 加载图像并进行预处理
        Image image = imageProcessor.preprocessImage(imagePath);

        // 提取图像特征
        Feature feature = featureExtractor.extractFeature(image);

        // 使用 KNN 算法进行预测
        int predictedDigit = knnModel.predict(feature, 5 /* K 值 */);

        return predictedDigit;
    }
};

// 加载训练数据
void loadTrainingData(const std::string& baseDirTrain, std::vector<Feature>& trainingFeatures, std::vector<int>& trainingLabels) {
    ImageProcessor imageProcessor;
    FeatureExtractor featureExtractor;

    for (int label = 0; label <= 9; ++label) {
        std::string dirPath = baseDirTrain + "\\" + std::to_string(label);
        for (int i = 1; i <= 10; ++i) {
            std::stringstream ss;
            ss << dirPath << "\\img" << label << i << ".txt";
            std::string filePath = ss.str();
            Image image = imageProcessor.preprocessImage(filePath);
            Feature feature = featureExtractor.extractFeature(image);
            trainingFeatures.push_back(feature);
            trainingLabels.push_back(label);
        }
    }
}

// 加载测试数据
void loadTestData(const std::string& baseDirTest, std::vector<std::string>& testFilePaths) {
    std::string dirPath = baseDirTest;

    // 遍历指定文件夹中的所有文件
    for (const auto& entry : std::filesystem::directory_iterator(dirPath)) {
        if (entry.path().extension() == ".txt") {
            testFilePaths.push_back(entry.path().string());
            
        }
    }
}

int main() {
    // 创建训练数据
    std::vector<Feature> trainingFeatures;
    std::vector<int> trainingLabels;

    // 训练数据路径
    std::string baseDirTrain = "C:\\Users\\DELL\\Desktop\\期末三期\\10_10";

    // 加载训练数据
    loadTrainingData(baseDirTrain, trainingFeatures, trainingLabels);

    // 创建数字识别器对象
    DigitRecognizer digitRecognizer(trainingFeatures, trainingLabels);

    // 训练数据路径
    std::string baseDirTest = "C:\\Users\\DELL\\Desktop\\期末三期\\txt\\2";

    // 加载测试数据
    std::vector<std::string> testFilePaths;
    loadTestData(baseDirTest, testFilePaths);

    // 执行数字识别并计算正确率
    int correctCount = 0;
    for (size_t i = 0; i < testFilePaths.size(); ++i) {
        int recognizedDigit = digitRecognizer.recognizeDigit(testFilePaths[i]);
        if (recognizedDigit == 2) {
            correctCount++;
        }
    }

    double accuracy = static_cast<double>(correctCount) / testFilePaths.size();

    // 输出识别结果
    std::cout << "2 Recognition Accuracy: " << accuracy * 100 << "%" << std::endl;

    return 0;
}