Python 在与 ElementTree 相同的循环中获取 XML 的父值和子值

Question

i manually constructed a XML file with desired annotations / pixel coordinates of image dataset, therefore i want to parse those annotations to single annotation object. This is my XML file:

<?xml version='1.0' encoding='ISO-8859-1'?>
<?xml-stylesheet type='text/xsl' href='image_metadata_stylesheet.xsl'?>

<images>
  <image file='pngCA43_01.jpg'>
    <box top='673' left='92' width='875' height='508'/>
  </image>
  <image file='pngCA43_02.jpg'>
    <box top='680' left='79' width='885' height='501'/>
  </image>
  <image file='pngCA43_03.jpg'>
    <box top='677' left='86' width='876' height='501'/>
  </image>
  <image file='pngCA43_04.jpg'>
    <box top='675' left='84' width='878' height='505'/>
  </image>
  <image file='pngCA43_05.jpg'>
    <box top='658' left='87' width='879' height='511'/>
  </image>

And goes on like this for 1000 lines. I want to access file, top, left, width and height parameters in the same loop. This is my python code:

import xml.etree.ElementTree as ET


class Annotation():
    name = ""
    top = 0
    left = 0
    width = 0
    height = 0

    def __init__(self, name, top, left, width, height):
        self.name = name
        self.top = top
        self.left = left
        self.width = width
        self.height = height

annotations = []
root_xml = ET.parse("xml/idcard.xml").getroot()
i = 1

for type_tag in root_xml.iter("box"):
    name = type_tag.get('file')
    top = type_tag.get('top')
    left = type_tag.get('left')
    width = type_tag.get('width')
    height = type_tag.get('height')
    print(f'{i}. Name: {name} Top: {top} Left: {left} Width: {width} Height: {height}\n')
    annotationObject = Annotation(name, top, left, width, height)
    annotations.append(annotationObject)
    i += 1

This snippet gives the output:

1. Name: None Top: 673 Left: 92 Width: 875 Height: 508

2. Name: None Top: 680 Left: 79 Width: 885 Height: 501

3. Name: None Top: 677 Left: 86 Width: 876 Height: 501

4. Name: None Top: 675 Left: 84 Width: 878 Height: 505

5. Name: None Top: 658 Left: 87 Width: 879 Height: 511

The parent node 'file' ( name of the image) is not present since i am iterating over the box node. However when i replace root_xml.iter("box") with root_xml.iter() , output is:

1. Name: None Top: None Left: None Width: None Height: None

2. Name: pngCA43_01.jpg Top: None Left: None Width: None Height: None

3. Name: None Top: 673 Left: 92 Width: 875 Height: 508

4. Name: pngCA43_02.jpg Top: None Left: None Width: None Height: None

5. Name: None Top: 680 Left: 79 Width: 885 Height: 501

6. Name: pngCA43_03.jpg Top: None Left: None Width: None Height: None

I can work with this by using 2 different loops and getting name from one loop and other attributes from second loop, but i'm sure there should be a way to do this, thanks for the help:) Stay safe!

Edit: Terms about XML might've been wrong, this is my first time working with XML's.

Answer 1

See below (find all 'image' elements and use a dataclass for Annotation)

import xml.etree.ElementTree as ET
from dataclasses import dataclass

XML = '''<images>
  <image file='pngCA43_01.jpg'>
    <box top='673' left='92' width='875' height='508'/>
  </image>
  <image file='pngCA43_02.jpg'>
    <box top='680' left='79' width='885' height='501'/>
  </image>
  <image file='pngCA43_03.jpg'>
    <box top='677' left='86' width='876' height='501'/>
  </image>
  <image file='pngCA43_04.jpg'>
    <box top='675' left='84' width='878' height='505'/>
  </image>
  <image file='pngCA43_05.jpg'>
    <box top='658' left='87' width='879' height='511'/>
  </image>
  </images>'''


@dataclass
class Annotation:
    name: str
    top: int
    left: int
    width: int
    height: int


root = ET.fromstring(XML)
annotations = [Annotation(i.attrib['file'], int(i.find('box').attrib['top']), int(i.find('box').attrib['left']),
                          int(i.find('box').attrib['width'])
                          , int(i.find('box').attrib['height'])) for i in root.findall('.//image')]
print(annotations)

output

[Annotation(name='pngCA43_01.jpg', top=673, left=92, width=875, height=508), Annotation(name='pngCA43_02.jpg', top=680, left=79, width=885, height=501), Annotation(name='pngCA43_03.jpg', top=677, left=86, width=876, height=501), Annotation(name='pngCA43_04.jpg', top=675, left=84, width=878, height=505), Annotation(name='pngCA43_05.jpg', top=658, left=87, width=879, height=511)]