{
  "MaskPolygonItem": {
    "0": {
      "BoundingBox": "354.105 221.957 379.764 96.2241",
      "label": "Number",
      "labelNum": 0,
      "polygon": "3,6"
    }
  },
  "channels": 3,
  "height": 1080,
  "width": 1920
}

#coding=utf-8 
import os
import json
#获取目标文件夹的路径
filedir = r'J:\NumberData\mrcnnHik\test'
#获取文件夹中的文件名称列表 
filenames=os.listdir(filedir)
#遍历文件名
for filename in filenames:
  filepath = filedir+'/'+filename
  # print(filepath)
  after = []
  # 打开文件取出数据并修改，然后存入变量
  with open(filepath, 'r') as f:
    data = json.load(f)
    mask=data["MaskPolygonItem"]
    for zidian in mask:
      print(type(zidian))
      mask[zidian]["polygon"] = '354 221,355 310,729 318,733 236'
    after = data
  # 打开文件并覆盖写入修改后内容
  with open(filepath, 'w') as f:
    #结构化输出
    data = json.dump(after, f,sort_keys=True, indent=4, separators=(',', ': '))

{
  "MaskPolygonItem": {
    "0": {
      "BoundingBox": "354.105 221.957 379.764 96.2241",
      "label": "Number",
      "labelNum": 0,
      "polygon": "354 221,355 310,729 318,733 236"
    }
  },
  "channels": 3,
  "height": 1080,
  "width": 1920
}