labelme标注出来的标注文件格式是json文件，在利用yolo进行训练时，要使用YOLO格式的数据。

import cv2
import os
import json
import shutil
import numpy as np
from pathlib import Path
from glob import glob
from tqdm import tqdm
 
id2cls = {0: 'pen'}
cls2id = {'pen': 0}
 
#支持中文路径
def cv_imread(filePath):
    cv_img=cv2.imdecode(np.fromfile(filePath,dtype=np.uint8),flags=cv2.IMREAD_COLOR)
    return cv_img
 
def labelme2yolo_single(img_path,label_file):
    anno= json.load(open(label_file, "r", encoding="utf-8"))
    shapes = anno['shapes']
    w0, h0 = anno['imageWidth'], anno['imageHeight']
    image_path = os.path.basename(img_path + anno['imagePath'])
    labels = []
    for s in shapes:
        pts = s['points']
        x1, y1 = pts[0]
        x2, y2 = pts[1]
        x = round((x1 + x2) / 2 / w0, 8)
        y = round((y1 + y2) / 2 / h0, 8)
        w = round(abs(x2 - x1) / w0, 8)
        h = round(abs(y2 - y1) / h0, 8)
        cid = cls2id[s['label']]        
        labels.append([cid, x, y, w, h])
    return np.array(labels, dtype=float), image_path
 
#这里的定位信息，xywh我选择了精确到小数点后第八位，可以根据需要随意修改。

# 确保所有数据都是数值类型


 
def labelme2yolo(img_path,labelme_label_dir, save_dir='res/'):
    labelme_label_dir = str(Path(labelme_label_dir)) + '/'
    save_dir = str(Path(save_dir))
    yolo_label_dir = save_dir + '/'
    """ yolo_image_dir = save_dir + 'images/'
    if not os.path.exists(yolo_image_dir):
        os.makedirs(yolo_image_dir) """
    if not os.path.exists(yolo_label_dir):
        os.makedirs(yolo_label_dir)
 
    json_files = glob(labelme_label_dir + '*.json')
    img_files = glob(img_path + '/*.jpg') + glob(img_path + '/*.png')  # 假设图像文件是jpg或png格式
    
    for jf in tqdm(json_files, desc="Processing JSON files"):
        filename = os.path.basename(jf).rsplit('.', 1)[0]
        labels, image_path = labelme2yolo_single(img_path,jf)
        if len(labels) > 0:
            np.savetxt(yolo_label_dir + filename + '.txt', labels, fmt='%d %.8f %.8f %.8f %.8f')
            
      # 处理没有对应json文件的图像文件
    for img_file in tqdm(img_files, desc="Processing image files"):
        filename = os.path.basename(img_file).rsplit('.', 1)[0]
        txt_file = yolo_label_dir + filename + '.txt'
        if not os.path.exists(txt_file):
            open(txt_file, 'w').close()  # 创建一个空白的txt文件
            # shutil.copy(labelme_label_dir + image_path, yolo_image_dir + image_path)
    print('Completed!')images
    
if __name__ == '__main__':
    img_path = 'F:/***/***/images/'   # 数据集图片的路径
    json_dir = 'F:/***/***/json'    # json标签的路径
    save_dir = 'F:/***/***/txt/'     # 保存的txt标签的路径
    labelme2yolo(img_path,json_dir, save_dir)