13

使用 lxml 的 ElementTree API 实现很容易从 XML 文档中完全删除给定元素，但是我看不到用一些文本一致地替换元素的简单方法。例如，给定以下输入：

input = '''<everything>
<m>Some text before <r/></m>
<m><r/> and some text after.</m>
<m><r/></m>
<m>Text before <r/> and after</m>
<m><b/> Text after a sibling <r/> Text before a sibling<b/></m>
</everything>
'''

...您可以使用以下方法轻松删除每个<r>元素：

from lxml import etree
f = etree.fromstring(data)
for r in f.xpath('//r'):
    r.getparent().remove(r)
print etree.tostring(f, pretty_print=True)

但是，您将如何用文本替换每个元素以获取输出：

<everything>
<m>Some text before DELETED</m>
<m>DELETED and some text after.</m>
<m>DELETED</m>
<m>Text before DELETED and after</m>
<m><b/>Text after a sibling DELETED Text before a sibling<b/></m>
</everything>

在我看来，因为 ElementTree API 通过每个元素的.textand.tail属性而不是树中的节点来处理文本，这意味着您必须根据元素是否具有兄弟元素来处理许多不同的情况，是否现有元素有一个.tail属性，依此类推。我错过了一些简单的方法吗？

4

3 回答 3

20

我认为 unutbu 的 XSLT 解决方案可能是实现目标的正确方法。

然而，这里有一个有点老套的方法来实现它，通过修改<r/>标签的尾部，然后使用etree.strip_elements.

from lxml import etree

data = '''<everything>
<m>Some text before <r/></m>
<m><r/> and some text after.</m>
<m><r/></m>
<m>Text before <r/> and after</m>
<m><b/> Text after a sibling <r/> Text before a sibling<b/></m>
</everything>
'''

f = etree.fromstring(data)
for r in f.xpath('//r'):
  r.tail = 'DELETED' + r.tail if r.tail else 'DELETED'

etree.strip_elements(f,'r',with_tail=False)

print etree.tostring(f,pretty_print=True)

给你：

<everything>
<m>Some text before DELETED</m>
<m>DELETED and some text after.</m>
<m>DELETED</m>
<m>Text before DELETED and after</m>
<m><b/> Text after a sibling DELETED Text before a sibling<b/></m>
</everything>
于 2011-03-24T14:13:54.763 回答
8

使用strip_elements的缺点是你不能让它保留一些<r>元素而替换其他元素。它还要求存在一个ElementTree实例（可能并非如此）。最后，您不能使用它来替换 XML 注释或处理指令。以下应该做你的工作： 

for r in f.xpath('//r'):
    text = 'DELETED' + r.tail 
    parent = r.getparent()
    if parent is not None:
        previous = r.getprevious()
        if previous is not None:
            previous.tail = (previous.tail or '') + text
        else:
            parent.text = (parent.text or '') + text
        parent.remove(r)
于 2012-05-09T16:50:24.630 回答
4

使用ET.XSLT：

import io
import lxml.etree as ET

data = '''<everything>
<m>Some text before <r/></m>
<m><r/> and some text after.</m>
<m><r/></m>
<m>Text before <r/> and after</m>
<m><b/> Text after a sibling <r/> Text before a sibling<b/></m>
</everything>
'''

f=ET.fromstring(data)
xslt='''\
    <xsl:stylesheet version="1.0"
        xmlns:xsl="http://www.w3.org/1999/XSL/Transform">    

    <!-- Replace r nodes with DELETED
         http://www.w3schools.com/xsl/el_template.asp -->
    <xsl:template match="r">DELETED</xsl:template>

    <!-- How to copy XML without changes
         http://mrhaki.blogspot.com/2008/07/copy-xml-as-is-with-xslt.html -->    
    <xsl:template match="*">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="@*|text()|comment()|processing-instruction">
        <xsl:copy-of select="."/>
    </xsl:template>
    </xsl:stylesheet>
'''

xslt_doc=ET.parse(io.BytesIO(xslt))
transform=ET.XSLT(xslt_doc)
f=transform(f)

print(ET.tostring(f))

产量

<everything>
<m>Some text before DELETED</m>
<m>DELETED and some text after.</m>
<m>DELETED</m>
<m>Text before DELETED and after</m>
<m><b/> Text after a sibling DELETED Text before a sibling<b/></m>
</everything>
于 2011-03-24T12:31:48.633 回答