使用不同长度的数组遍历 XML 数据

原文标题 ：Iterate through XML data with arrays of different lengths

我有一个 XML 文件，其中包含摄影测量中使用的连接点。我正在尝试使用 Python 来提取已用于每个连接点的纬度、经度、高度和图像 ID。

XML数据如下

<?xml version="1.0" encoding="utf-8"?>
<TiePoints>
    <TiePoint>
        <Position>
            <x>127.915511902581</x>
            <y>-33.4353126218486</y>
            <z>16.4129273099825</z>
        </Position>
        <Color>
            <Red>0.474509803921569</Red>
            <Green>0.403921568627451</Green>
            <Blue>0.325490196078431</Blue>
        </Color>
        <Measurement>
            <PhotoId>2</PhotoId>
            <x>3693.80004882812</x>
            <y>925.170166015625</y>
        </Measurement>
        <Measurement>
            <PhotoId>3</PhotoId>
            <x>3671.1689453125</x>
            <y>2261.18017578125</y>
        </Measurement>
        <Measurement>
            <PhotoId>22</PhotoId>
            <x>3706.51635742188</x>
            <y>1812.31091308594</y>
        </Measurement>
    </TiePoint>
    <TiePoint>
        <Position>
            <x>127.915470841975</x>
            <y>-33.4353080715225</y>
            <z>16.2808672133833</z>
        </Position>
        <Color>
            <Red>0.63921568627451</Red>
            <Green>0.572549019607843</Green>
            <Blue>0.466666666666667</Blue>
        </Color>
        <Measurement>
            <PhotoId>2</PhotoId>
            <x>3184.81469726562</x>
            <y>928.787292480469</y>
        </Measurement>
        <Measurement>
            <PhotoId>3</PhotoId>
            <x>3155.33715820312</x>
            <y>2289.67504882812</y>
        </Measurement>
        <Measurement>
            <PhotoId>22</PhotoId>
            <x>4187.51220703125</x>
            <y>1816.5751953125</y>
        </Measurement>
        <Measurement>
            <PhotoId>518</PhotoId>
            <x>2024.55029296875</x>
            <y>959.028137207031</y>
        </Measurement>
        <Measurement>
            <PhotoId>519</PhotoId>
            <x>1895.59228515625</x>
            <y>1790.13635253906</y>
        </Measurement>
    </TiePoint>

我面临的问题是每个连接点使用的照片数量不同（从 3 到 6+），由 PhotoID 表示。我已经把我正在使用的代码放在下面。

当我运行下面的代码时，我得到一个 TypeError: ‘NoneType’ object is not iterable。我是使用 Python 的新手，并且知道我使用 for 循环的方式可能不正确，但我现在不知道该怎么做。

任何帮助将不胜感激！

import pandas as pd
import numpy as np
import ntpath as nt

import xml.etree.cElementTree as et
import pandas as pd
tree=et.parse('TiePoints.xml')
root=tree.getroot()

TiePoint = []
PosX = []
PosY = []
PosZ = []
PhotoId1 = []
PhotoId2 = []
PhotoId3 = []
PhotoId4 = []
PhotoId5 = []
n = -1
i = 1

for tiepoint in root.findall("TiePoint"):
    n = n + i
    TiePoint.append(n)
    for posx in tiepoint.findall(".//Position/x"):
        PosX.append(posx.text)
    for posy in tiepoint.findall(".//Position/y"):
        PosY.append(posy.text)
    for posz in tiepoint.findall(".//Position/z"):
        PosZ.append(posz.text)
    for photoid1 in tiepoint.find(".//Measurement[1]/PhotoId[1]"):
        PhotoId1.append(photoid1.text)
    for photoid2 in tiepoint.find(".//Measurement[2]/PhotoId[1]"):
        PhotoId2.append(photoid2.text)  
    for photoid3 in tiepoint.find(".//Measurement[3]/PhotoId[1]"):
        PhotoId3.append(photoid3.text) 
    for photoid4 in tiepoint.find(".//Measurement[4]/PhotoId[1]"):
        PhotoId4.append(photoid4.text)

TiePoints_df = pd.DataFrame(list(zip(TiePoint,PosX,PosY,PosZ,PhotoId1,PhotoId2,PhotoId3,PhotoId4,PhotoId5)),columns=['Tie Point','Pos X','Pos Y','Pos Z','PhotoID 1','PhotoID 2','PhotoID 3','PhotoID 4','PhotoID 5'])

TiePoints_df.head()

TiePoints_df.to_csv("tiepoints-converted.csv")