Question

我有一个很长的html文档，我知道其中某些文本的确切位置。例如：

<html>
  <body>
    <div>
      <a>
        <b>
          I know the exact position of this text
        </b>
        <i>
          Another text
        </i>
      </a>
    </div>
  </body>
</html>

我知道这句话“我知道这段文字的确切位置”从字母编号'x'开始，到字符编号'y'结束。但是我必须得到整个标记/ node / element，它保存了这个值。可能有几个是它的祖先。

我如何轻松处理它？</ p>

//修改

要明确说明 - 我唯一得到的是一个整数值，它描述了句子的开头。

例如 - 2048。

我不能假设任何有关文档结构的内容。从某些方面开始，我必须在整个节点中由祖先进行祖先。

即使是位置（2048）指出的句子也不一定是唯一的。

Answer 1

假设<b>在此实例中是唯一的，您可以将XPath与xml.etree.elementtree一起使用。

import xml.etree.elementtree as ET
tree = ET.parse('xmlfile')
root = tree.get(root)
myEle = root.findall(".//*[b]")

myEle现在将保留对'b'的父级的引用，在本例中为'a'。

如果您只想要b元素，那么您可以这样做：

myEle = root.findall(".//b")

如果你想要a的孩子，你可以做几件不同的事情：

myEle = root.findall(".//a//")
myEle = root.findall('.//*[a]//*')[1:]

有关XPath的更多信息，请查看此处：XPath

Answer 2

您可以将整个HTML文档的内容作为字符串阅读。然后，您可以使用标记（具有唯一ID的HTML锚元素）获取修改后的字符串，并使用xml.etree.ElementTree解析字符串，就像标记位于原始文档中一样。然后，您可以使用XPath找到标记的父元素，并删除辅助标记。结果包含结构，就像解析原始doc一样。但是现在你知道带有文字的元素了！

警告：您必须知道位置是字节位置还是抽象字符位置。（想想多字节编码或编码某些字符的非固定长度的序列。还要考虑行结尾 - 一个或两个字节。）

尝试使用Windows行结尾将问题中的示例存储在data.html中的示例：

#!python3

import xml.etree.ElementTree as ET

fname = 'doc.html'
pos = 64

with open(fname, encoding='utf-8') as f:
    content = f.read()

# The position_id will be used in XPath, the position_anchor
# uses the variable only for readability. The position anchor
# has the form of an HTML element to be found easily using 
# the XPath expression.
position_id = 'my_unique_position_{}'.format(pos)
position_anchor = '<a id="{}" />'.format(position_id)

# The modified content has one extra anchor as the position marker.
modified_content = content[:pos] + position_anchor + content[pos:]

root = ET.fromstring(modified_content)
ET.dump(root)
print('----------------')

# Now some examples for getting the info around the point.
# '.' = from here; '//' = wherever; 'a[@id=...]' = anchor (a) element
# with the attribute id with the value. 
# We will not use it later -- only for demonstration.
anchor_element = root.find('.//a[@id="{}"]'.format(position_id))
ET.dump(anchor_element)
print('----------------')

# The text at the original position -- the text became the tail 
# of the element.
print(repr(anchor_element.tail))
print('================')

# Now, from scratch, get the nearest parent from the position.
parent = root.find('.//a[@id="{}"]/..'.format(position_id))
ET.dump(parent)
print('----------------')

# ... and the anchor element (again) as the nearest child
# with the attributes.
anchor = parent.find('./a[@id="{}"]'.format(position_id))
ET.dump(anchor)
print('----------------')

# If the marker split the text, part of the text belongs to 
# the parent, part is the tail of the anchor marker.
print(repr(parent.text))
print(repr(anchor.tail))
print('----------------')

# Modify the parent to remove the anchor element (to get
# the original structure without the marker. Do not forget
# that the text became the part of the marker element as the tail.
parent.remove(anchor)
parent.text += anchor.tail
ET.dump(parent)
print('----------------')

# The structure of the whole document now does not contain 
# the added anchor marker, and you get the reference
# to the nearest parent.
ET.dump(root)
print('----------------')

它打印以下内容：

c:\_Python\Dejwi\so25370255>a.py
<html>
  <body>
    <div>
      <a>
        <b>
          I know<a id="my_unique_position_64" /> the exact position of this text

        </b>
        <i>
          Another text
        </i>
      </a>
    </div>
  </body>
</html>
----------------
<a id="my_unique_position_64" /> the exact position of this text

----------------
' the exact position of this text\n        '
================
<b>
          I know<a id="my_unique_position_64" /> the exact position of this text

        </b>

----------------
<a id="my_unique_position_64" /> the exact position of this text

----------------
'\n          I know'
' the exact position of this text\n        '
----------------
<b>
          I know the exact position of this text
        </b>

----------------
<html>
  <body>
    <div>
      <a>
        <b>
          I know the exact position of this text
        </b>
        <i>
          Another text
        </i>
      </a>
    </div>
  </body>
</html>
----------------

Python从精确位置获取HTML元素/节点/标记

2 个答案: