Java实现KNN算法填充Excel缺失值

package org.example;

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.Collections; import java.util.Comparator; import java.util.Date; import java.util.List;

import org.apache.poi.ss.usermodel.Cell; import org.apache.poi.ss.usermodel.CellType; import org.apache.poi.ss.usermodel.Row; import org.apache.poi.ss.usermodel.Sheet; import org.apache.poi.ss.usermodel.Workbook; import org.apache.poi.ss.usermodel.WorkbookFactory;

public class knn {

public static void main(String[] args) {
    String inputFile = 'input.xlsx';
    String outputFile = 'output1.xlsx';
    try (Workbook workbook = WorkbookFactory.create(new FileInputStream(inputFile));
         FileOutputStream outputStream = new FileOutputStream(outputFile)) {
        Sheet sheet = workbook.getSheetAt(0);
        DecimalFormat df = new DecimalFormat('#.##');
        for (int i = 1; i <= sheet.getLastRowNum(); i++) {
            Row row = sheet.getRow(i);
            if (row != null) {
                Cell cell = row.getCell(1);
                if (cell != null && cell.getCellType() != CellType.BLANK) {
                    // 如果单元格不为空，则跳过
                } else {
                    double avg = calculateKNN(sheet, i, 1);
                    if (avg > 0) {
                        if(cell == null){
                            cell = row.createCell(1);
                        }
                        cell.setCellValue(Double.parseDouble(df.format(avg)));
                    }
                }
            }
        }
        workbook.write(outputStream);
        System.out.println('Data filling completed.');
    } catch (Exception e) {
        e.printStackTrace();
    }
}

private static double calculateKNN(Sheet sheet, int rowIndex, int columnIndex) {
    List<Double> data = new ArrayList<Double>();
    for (int i = 0; i <= sheet.getLastRowNum(); i++) {
        Row row = sheet.getRow(i);
        if (row != null) {
            Cell cell = row.getCell(columnIndex);
            if (cell != null && cell.getCellType() == CellType.NUMERIC) {
                data.add(cell.getNumericCellValue());
            }
        }
    }
    if (data.size() > 0) {
        double missingValue = 0;
        Row row = sheet.getRow(rowIndex);
        if (row != null) {
            Cell cell = row.getCell(columnIndex);
            if (cell == null || cell.getCellType() == CellType.BLANK) {
                missingValue = 0;
            } else if (cell.getCellType() == CellType.NUMERIC) {
                missingValue = cell.getNumericCellValue();
            } else if (cell.getCellType() == CellType.STRING) {
                try {
                    missingValue = Double.parseDouble(cell.getStringCellValue());
                } catch (NumberFormatException e) {
                    missingValue = 0;
                }
            }
        }
        if (missingValue > 0) {
            return missingValue;
        } else {
            List<Double> distances = new ArrayList<Double>();
            for (double value : data) {
                double distance = Math.abs(value - missingValue);
                distances.add(distance);
            }
            Collections.sort(distances, new Comparator<Double>() {
                @Override
                public int compare(Double o1, Double o2) {
                    return Double.compare(o1, o2);
                }
            });
            int k = 3;
            double sum = 0;
            int count = 0;
            for (int i = 0; i < k && i < distances.size(); i++) {
                double value = data.get(distances.indexOf(distances.get(i)));
                sum += value;
                count++;
            }
            if (count > 0) {
                return sum / count;
            } else {
                return 0;
            }
        }
    } else {
        return 0;
    }
}

private static Date parseDate(String dateString) {
    SimpleDateFormat dateFormat = new SimpleDateFormat('yyyy/MM/dd HH:mm');
    try {
        return dateFormat.parse(dateString);
    } catch (ParseException e) {
        e.printStackTrace();
        return null;
    }
}

}