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问python正则表达式查找并替换具有特定属性值的html标记
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Stack Overflow用户

提问于 2013-12-15 14:43:52

回答 2查看 2.2K关注 0票数 3

我试图在python中编写一个正则表达式，该表达式将找到src属性等于特定值的所有img标记。我试着写以下内容

   # where thm equal /public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82
   p = re.compile(r'<img.*?%s.*?>' % thm)
   print p.pattern
   print p.sub(linked_image, c)

低于我的产出

<img.*?/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82.*?>

<p><img src="/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82" alt=""></p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf </p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf 
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf

python

regex

回答 2

Stack Overflow用户

回答已采纳

发布于 2013-12-17 08:57:56

-- LXML的解决方案

为了将解决方案与正则表达式和LXML进行比较，我创建了另一篇文章：

一个更容易和更稳定的解决方案是将lxml与etree结合使用。在该解决方案中，您访问某些DOM元素并对它们进行编辑。

转换HTML并使其通过正确的xpath，例如.//img。xpath返回可以get和set src属性的所有已找到元素的列表。函数etree.tostring(tree)返回一个编辑过的字符串：

from lxml import etree
tree = etree.HTML('''<html>
                     <body>
                        <h1>Title</h1>
                        <img src="/media/old/another_logo.png" alt="" />
                        <p>Lorem Ipsum</p>
                        <p><img src="/media/old/logo.png" alt=""/></p>
                     </body>
                  </html>''')

imgs = tree.xpath('.//img')

for img in imgs:
    print 'OLD_SOURCE', img.get('src')
    img.set('src', '/media/new/python.jpg')

print etree.tostring(tree)

输出

OLD_SOURCE /media/old/another_logo.png
OLD_SOURCE /media/old/logo.png

<html>
    <body>
        <h1>Title</h1>
            <img src="/media/new/python.jpg" alt=""/>
            <p>Lorem Ipsum</p>
            <p><img src="/media/new/python.jpg" alt=""/></p>
    </body>
</html>

票数 2

Stack Overflow用户

发布于 2013-12-15 15:10:40

正则表达式的解决方案

我意识到插入到thm中的字符串没有转义。因此，在将其添加到正则表达式之前，您需要用正则表达式语言中的附加意义来转义所有符号--这里、?和.。

我用[?]{1}代替了?，用\.代替了.。得到的正则表达式现在与测试字符串匹配。

import re
thm = '/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82'

all_html_code = '''<img.*?/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82.*?>

<p><img src="/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82" alt=""></p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf </p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf
</p><p>lksj lksdfj lsdkfj sldkfj sldkfj lskdfj lsjf lksjf lksj flksdjf klsj flk dkj sdlkfj sdlkfj sldkjf sldkfj lsdkjf lskjflsjfsl lksdjf '''

escaped_thm = thm.replace('.', '\.').replace('?','[?]{1}')
p = re.compile(r'<img.*?src="(%s)".*?>' % escaped_thm)

test_img = '''<img src="/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82" alt="">'''
print p.match(test_img)

new_img_tag = '<img src="/python/logo.jpg" alt=""/>'
print p.sub(new_img_tag, all_html_code)

顺便问一下，你为什么要找<img src=""...>？您可以直接替换src属性：

escaped_thm = thm.replace('.', '\.').replace('?','[?]{1}')
p = re.compile(r'src="(%s)"' % escaped_thm)

replacement = '''src="/python/logo.jpg"'''
print p.sub(replacement, all_html_code)

输出1

<_sre.SRE_Match object at 0x... >
<img.*?/public_media/cache/84/b5/84b59e293cbdb7041b68a84977d62cf3.jpg?image_pk=82.*?>

<p><img src="/python/logo.jpg" alt=""/></p><p>lksj lksdfj ... lksdjf

输出2

<p><img src="/python/logo.jpg" alt=""></p><p>lksj lksdfj ... lksdjf

在询问了如何正确地转义正则表达式符号(Regular expression to escape regular expressions)之后，我可以推荐一个re.escape，而不是两个replace方法。

使用LXML

您需要使用正则表达式吗？HTML的正则表达式可能有很大的问题。在这里看到更多信息和精彩的帖子(RegEx match open tags except XHTML self-contained tags)。

我宁愿像这里一样使用XPath。

票数 1

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/20595735

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