python - 没有在 python 中正确解析嵌套的 xml 标签

Question

我在 python 中处理 XML 文件。我有一个包含多种语言的句子的数据集，其结构如下:

<corpus>
  <sentence id="0">
    <text lang="de">...</text>
    <text lang="en">...</text>
    <text lang="fr">...</text>
    <!-- Other languages -->
    <annotations>
      <annotation lang="de">...</annotation>
      <annotation lang="en">...</annotation>
      <annotation lang="fr">...</annotation>
      <!-- Other languages -->
    </annotations>
  </sentence>
  <sentence id="1">
    <!-- Other sentence -->
  </sentence>
  <!-- Other sentences -->
</corpus>

我想得到的是，从数据集开始，一个新的数据集只包含句子和英文注释(属性“lang”的“en”值)。我试过这个解决方案:

import xml.etree.ElementTree as ET
tree = ET.parse('samplefile2.xml')
root = tree.getroot()
for sentence in root:
  if sentence.tag == 'sentence':
    for txt in sentence:
      if txt.tag == 'text':
        if txt.attrib['lang'] != 'en':
          sentence.remove(txt)
      if txt.tag == 'annotations':
        for annotation in txt:
          if annotation.attrib['lang'] != 'en':
            txt.remove(annotation)
tree.write('output.xml')

但是好像只在text属性层面起作用，在annotation属性层面不起作用。我什至尝试用增量索引 root[s]、root[s][t]、root[s][t ][a]，但是排序没有效果。此外，我提供的 python 代码在 xml 文件中随机插入(老实说，我不知道这是否有助于解决这个问题)像 δημι 这样的字符串;ουργία。

所以，我坚信问题出在嵌套标签中，但我无法弄清楚。一些想法？

Answer 1

如果您能够使用 lxml，我认为使用 xpath 会更容易...

XML 输入 (input.xml)

<corpus>
  <sentence id="0">
    <text lang="de">...</text>
    <text lang="en">...</text>
    <text lang="fr">...</text>
    <!-- Other languages -->
    <annotations>
      <annotation lang="de">...</annotation>
      <annotation lang="en">...</annotation>
      <annotation lang="fr">...</annotation>
      <!-- Other languages -->
    </annotations>
  </sentence>
  <sentence id="1">
    <!-- Other sentence -->
  </sentence>
  <!-- Other sentences -->
</corpus>

python

from lxml import etree

target_lang = "en"

tree = etree.parse("input.xml")

# Match any element that has a child that has a lang attribute with a value other than
# target_lang. We need this element so we can remove the child from it.
for parent in tree.xpath(f".//*[*[@lang != '{target_lang}']]"):
    # Match the children that have a lang attribute with a value other than target_lang.
    for child in parent.xpath(f"*[@lang != '{target_lang}']"):
        # Remove the child from the parent.
        parent.remove(child)

tree.write("output.xml")

XML 输出 (output.xml)

<corpus>
  <sentence id="0">
    <text lang="en">...</text>
    <!-- Other languages -->
    <annotations>
      <annotation lang="en">...</annotation>
      <!-- Other languages -->
    </annotations>
  </sentence>
  <sentence id="1">
    <!-- Other sentence -->
  </sentence>
  <!-- Other sentences -->
</corpus>