Excel 数据填充算法：EM 算法结合日期插值

package Data_Recovery;

import org.apache.poi.ss.usermodel.*;

import java.io.FileInputStream; import java.io.FileOutputStream; import java.text.DecimalFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.List;

public class EM03 {

public static void main(String[] args) {
    // 定义输入文件和输出文件的路径
    String inputFile = "input-2.xlsx";
    try (Workbook workbook = WorkbookFactory.create(new FileInputStream(inputFile))) { // 使用工作簿工厂创建 Excel 工作簿
        Sheet sheet = workbook.getSheet("P1"); // 获取 P1 工作表
        DecimalFormat df = new DecimalFormat("#.##"); // 创建 Decimal 格式化器，用于保留两位小数
        // 创建新的工作表
        String newSheetName = "P1-1";
        int sheetIndex = workbook.getSheetIndex(newSheetName);
        Sheet newDataSheet;
        if (sheetIndex >= 0) {
            workbook.removeSheetAt(sheetIndex);
        }
        newDataSheet = workbook.createSheet(newSheetName);
        // 复制原工作表的数据到新的工作表
        for (int i = 0; i <= sheet.getLastRowNum(); i++) {
            Row oldRow = sheet.getRow(i);
            Row newRow = newDataSheet.createRow(i);
            if (oldRow != null) {
                for (int j = 0; j < oldRow.getLastCellNum(); j++) {
                    Cell oldCell = oldRow.getCell(j);
                    Cell newCell = newRow.createCell(j);
                    if (oldCell != null) {
                        if(oldCell.getCellType() == CellType.STRING){
                            newCell.setCellValue(oldCell.getStringCellValue());
                        } else if(oldCell.getCellType() == CellType.NUMERIC){
                            newCell.setCellValue(oldCell.getNumericCellValue());
                        } else if(oldCell.getCellType() == CellType.BOOLEAN){
                            newCell.setCellValue(oldCell.getBooleanCellValue());
                        } else if(oldCell.getCellType() == CellType.FORMULA){
                            newCell.setCellValue(oldCell.getCellFormula());
                        } else if(oldCell.getCellType() == CellType.ERROR){
                            newCell.setCellValue(oldCell.getErrorCellValue());
                        }
                        // 复制原单元格的样式到新单元格
                        CellStyle oldCellStyle = oldCell.getCellStyle();
                        CellStyle newCellStyle = workbook.createCellStyle();
                        newCellStyle.cloneStyleFrom(oldCellStyle);
                        newCell.setCellStyle(newCellStyle);
                    }
                }
            }
        }
        // 插入缺失的时间
        insertMissingDates(newDataSheet);
        // 对每一行进行处理
        for (int i = 1; i <= newDataSheet.getLastRowNum(); i++) {
            Row row = newDataSheet.getRow(i); // 获取行对象
            if (row != null) {
                Cell cell = row.getCell(1); // 获取第二列单元格
                if (cell == null || cell.getCellType() == CellType.BLANK) { // 判断单元格是否为空或者空白
                    double avg = calculateEM(newDataSheet, i, 1); // 计算EM算法填充的值
                    if (avg > 0) { // 如果填充的值大于 0
                        cell = row.createCell(1); // 创建新的单元格
                        cell.setCellValue(Double.parseDouble(df.format(avg))); // 将填充的值填入单元格
                        // 设置单元格的数据类型为数值类型
                        CellStyle cellStyle = workbook.createCellStyle();
                        DataFormat dataFormat = workbook.createDataFormat();
                        cellStyle.setDataFormat(dataFormat.getFormat("0.00"));
                        cell.setCellStyle(cellStyle);
                    }
                }
            }
        }
        // 将工作簿写入输入文件
        FileOutputStream outputStream = new FileOutputStream(inputFile);
        workbook.write(outputStream);
        outputStream.close();
        System.out.println("Data filling completed."); // 输出信息
    } catch (Exception e) { // 捕获异常
        e.printStackTrace();
    }
}

// 计算EM算法填充的值
private static double calculateEM(Sheet sheet, int rowIndex, int columnIndex) {
    Row row;
    double missingValue = 0; // 缺失值
    row = sheet.getRow(rowIndex); // 获取当前行对象
    if (row != null) {
        Cell cell = row.getCell(columnIndex); // 获取指定列的单元格
        if (cell != null && cell.getCellType() == CellType.NUMERIC) {
            missingValue = cell.getNumericCellValue(); // 缺失值为单元格中的值
        } else if (cell != null && cell.getCellType() == CellType.STRING) {
            try {
                missingValue = Double.parseDouble(cell.getStringCellValue()); // 转换为数字类型
            } catch (NumberFormatException e) {
                missingValue = 0; // 转换失败则缺失值为 0
            }
        }
    }

    List<Double> data = new ArrayList<>(); // 存储数据
    for (int i = 0; i <= sheet.getLastRowNum(); i++) { // 对每一行进行处理
        row = sheet.getRow(i); // 获取行对象
        if (row != null) {
            Cell cell = row.getCell(columnIndex); // 获取指定列的单元格
            if (cell != null && cell.getCellType() == CellType.NUMERIC) {
                data.add(cell.getNumericCellValue()); // 将数据添加到列表中
            } else if (cell != null && cell.getCellType() == CellType.STRING) {
                try {
                    double value = Double.parseDouble(cell.getStringCellValue()); // 转换为数字类型
                    data.add(value); // 将数据添加到列表中
                } catch (NumberFormatException e) {
                    // 转换失败，忽略该值
                }
            }
        }
    }

    if (data.size() > 0 && missingValue >= 0) { // 如果存在数据且缺失值大于 0
        double sum = 0; // 总和
        int count = 0; // 非缺失值个数
        for (double value : data) { // 遍历数据
            if (value >= 0) { // 非缺失值
                sum += value; // 累加非缺失值
                count++; // 非缺失值个数加一
            }
        }
        if (count > 0) { // 如果存在非缺失值
            double average = sum / count; // 计算平均值
            double variance = 0; // 方差
            for (double value : data) { // 遍历数据
                if (value >= 0) { // 非缺失值
                    variance += Math.pow(value - average, 2); // 累加方差
                }
            }
            variance /= count; // 计算方差
            double stdDeviation = Math.sqrt(variance); // 标准差
            double filledValue = generateRandomValue(average, stdDeviation); // 生成符合正态分布的随机值
            return filledValue; // 返回填充的值
        }
    }
    return 0; // 如果不存在数据或缺失值小于等于0，返回 0
}

// 生成符合正态分布的随机值
private static double generateRandomValue(double average, double stdDeviation) {
    double value;
    do {
        value = average + stdDeviation * Math.random(); // 生成随机值
    } while (value < 0); // 保证生成的值大于等于 0
    return value;
}

// 解析日期
private static Date parseDate(String dateString) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm"); // 创建日期格式化器
    try {
        return dateFormat.parse(dateString); // 解析日期
    } catch (ParseException e) { // 捕获异常
        e.printStackTrace();
        return null; // 返回 null
    }
}

// 插入缺失的时间
private static void insertMissingDates(Sheet sheet) {
    int lastRowNum = sheet.getLastRowNum();
    for (int i = 1; i <= lastRowNum; i++) {
        Row currentRow = sheet.getRow(i);
        Row previousRow = sheet.getRow(i - 1);
        if (currentRow != null && previousRow != null) {
            Cell currentCell = currentRow.getCell(0);
            Cell previousCell = previousRow.getCell(0);
            if (currentCell != null && currentCell.getCellType() == CellType.STRING && previousCell != null && previousCell.getCellType() == CellType.STRING) {
                String currentDateStr = currentCell.getStringCellValue();
                String previousDateStr = previousCell.getStringCellValue();
                Date currentDate = parseDate(currentDateStr);
                Date previousDate = parseDate(previousDateStr);
                if (currentDate != null && previousDate != null) {
                    long diff = currentDate.getTime() - previousDate.getTime();
                    long diffDays = diff / (24 * 60 * 60 * 1000);
                    if (diffDays > 10) {
                        int insertCount = (int) (diffDays / 10);
                        for (int j = 1; j <= insertCount; j++) {
                            Date insertDate = new Date(previousDate.getTime() + j * 10 * 24 * 60 * 60 * 1000);
                            String insertDateStr = formatDate(insertDate);
                            Row insertRow = sheet.createRow(i + j);
                            Cell insertCell = insertRow.createCell(0);
                            insertCell.setCellValue(insertDateStr);
                        }
                        lastRowNum += insertCount;
                    }
                }
            }
        }
    }
}

// 格式化日期
private static String formatDate(Date date) {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm");
    return dateFormat.format(date);
}

}