labelimg标注的VOC格式标签xml文件和yolo格式标签txt文件相互转换

要实现VOC格式标签xml文件和YOLO格式标签txt文件的互相转换，需要编写相应的转换代码。以下是Python代码示例：

import os
import glob
import xml.etree.ElementTree as ET
import numpy as np
 
# VOC标签转YOLO标签
def convert_voc_to_yolo(xml_file, txt_file, classes):
    with open(txt_file, 'w') as f:
        tree = ET.parse(xml_file)
        root = tree.getroot()
        size = root.find('size')
        w = int(size.find('width').text)
        h = int(size.find('height').text)
        
        for obj in root.iter('object'):
            cls = obj.find('name').text
            if cls not in classes:
                continue
            cls_id = classes.index(cls)
            xml_box = obj.find('bndbox')
            xmin = int(xml_box.find('xmin').text)
            ymin = int(xml_box.find('ymin').text)
            xmax = int(xml_box.find('xmax').text)
            ymax = int(xml_box.find('ymax').text)
            x_center = (xmin + xmax) / 2 / w
            y_center = (ymin + ymax) / 2 / h
            width = (xmax - xmin) / w
            height = (ymax - ymin) / h
            f.write(' '.join([str(cls_id), str(x_center), str(y_center), str(width), str(height)]) + '\n')
 
# YOLO标签转VOC标签
def convert_yolo_to_voc(txt_file, xml_file, classes):
    tree = ET.parse(xml_file)
    root = tree.getroot()
    size = root.find('size')
    w = int(size.find('width').text)
    h = int(size.find('height').text)
    
    with open(txt_file, 'r') as f:
        lines = f.readlines()
    
    for line in lines:
        cls_id, x_center, y_center, width, height = [float(x) for x in line.split()]
        xmin = int((2 * x_center * w) - (width * w))
        ymin = int((2 * y_center * h) - (height * h))
        xmax = int(xmin + (width * w))
        ymax = int(ymin + (height * h))
        
        obj = ET.Element('object')
        name = ET.SubElement(obj, 'name')
        name.text = classes[int(cls_id)]
        bndbox = ET.SubElement(obj, 'bndbox')
        xmin_tag = ET.SubElement(bndbox, 'xmin')
        xmin_tag.text = str(xmin)
        ymi