将文件夹下的xml文件转换为txt到另一个文件，但是生成的txt文件是空的是为什么呢

将文件夹下的xml文件转换为txt到另一个文件，但是生成的txt文件是空的是为什么呢
xml文件内容是这样的

<annotation>
    <folder>20160523folder>
    <filename>XRay20160523153057.bmpfilename>
    <path>\\192.168.31.118\share\ImageLabel\20160523\XRay20160523153057.bmppath>
    <source>
        <database>Unknowndatabase>
    source>
    <size>
        <width>1024width>
        <height>768height>
        <depth>3depth>
    size>
    <segmented>0segmented>
    <object>
        <name>mobilephonename>
        <pose>Unspecifiedpose>
        <truncated>0truncated>
        <difficult>0difficult>
        <bndbox>
            <xmin>268xmin>
            <ymin>384ymin>
            <xmax>340xmax>
            <ymax>434ymax>
        bndbox>
    object>
    <object>
        <name>sword_middlename>
        <pose>Unspecifiedpose>
        <truncated>0truncated>
        <difficult>0difficult>
        <bndbox>
            <xmin>291xmin>
            <ymin>405ymin>
            <xmax>393xmax>
            <ymax>472ymax>
        bndbox>
    object>
    <object>
        <name>gun_mausename>
        <pose>Unspecifiedpose>
        <truncated>0truncated>
        <difficult>0difficult>
        <bndbox>
            <xmin>332xmin>
            <ymin>352ymin>
            <xmax>442xmax>
            <ymax>414ymax>
        bndbox>
    object>
annotation>

import xml.etree.ElementTree as ET
import os
# 类别
CLASSES=["glassbottle","knife","middleknife","bigknife","gun","computer","mobile","bottle"]
# xml文件路径
#xml_input="D:\\temp\\yolov7-main\\data\\dataset_one\\labels\\train\\"
xml_input = "D:\\temp\\yolov7-main\\data\\dataset_one\\labels\\valid\\"
#txt_output="D:\\temp\\yolov7-main\\data\\dataset_one\\labels\\trainTXT\\"
txt_output = "D:\\temp\\yolov7-main\\data\\dataset_one\\labels\\validTXT"
def convert(size,box):
    # 将bbox的左上角点，右下角点坐标的格式，转换为bbox中心点+bbox的W,H的格式，并进行归一化
    dw=1./size[0]
    dh=1./size[1]
    x=(box[0]+box[1])/2.0
    y=(box[2]+box[3])/2.0
    w=box[1]-box[0]
    h=box[3]-box[2]
    x=x*dw
    w=w*dw
    y=y*dh
    h=h*dh
    return (x,y,w,h)
def convert_annotation(image_id):
    # 把图像image_id的xml文件转换为目标检测的label文件(txt)
    # 其中包含物体的类别cls,bbox的中心点坐标,以及bbox的W,H
    # 并将四个物理量归一化

    in_file=open(xml_input+image_id)
    image_id=image_id.split(".")[0]
    #  out_file=open(txt_output+"txt/%s.txt"%(image_id),"w")

    out_file = open(txt_output + "%s.txt" % (image_id), "w")
    tree=ET.parse(in_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"):
        difficult=obj.find("difficult").text
        obj_cls=obj.find("name").text
        if obj_cls not in CLASSES or int(difficult)==1:
            continue
        cls_id=CLASSES.index(obj_cls)
        xmlbox=obj.find("bndbox")
        points=(float(xmlbox.find("xmin").text),
                float(xmlbox.find("xmax").text),
                float(xmlbox.find("ymin").text),
                float(xmlbox.find("ymax").text))
        bb=convert((w,h),points)
        out_file.write(str(cls_id)+" "+" ".join([str(a) for a in bb])+"\n")
def make_label_txt():
    # labels文件夹下创建image_id.txt
    # 对应每个image_id.xml提取出的bbox信息
    filenames=os.listdir(xml_input)
    for file in filenames:
        convert_annotation(file)

if __name__=="__main__":
    # 开始提取和转换
    make_label_txt()

你把input内容打印一下，会不会是取出来就是空内容

root.iter("object")是啥，没有这个标签，是空的，循环根本没走啊
object是在annotation标签下面的，不是在root下面的