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Python re.sub替换html属性

[英]Python re.sub replace html attributes

I'm trying to resize images from html code. 我正在尝试从html代码调整图像大小。 This is one example: 这是一个例子:

My goal is to substitute " height="108" " and " width="150" with height and width 400. I've tried the following lines, though they don't seem to work: 我的目标是用高度和宽度400替换" height="108" ”和" width="150" 。我尝试了以下几行,尽管它们似乎不起作用:

re.sub(r'width="[0-9]{2,4}"','width="400"',x)
re.sub(r'height="[0-9]{2,4}"','height="400"',x)

Does anyone have a solution for this? 有人有解决方案吗? Ps: I'm not that good at Regex... :) Ps:我对Regex并不擅长...... :)

The reason it does not work is because strings are immutable , and you do not process the result. 它不起作用的原因是因为字符串是不可变的 ,并且您不处理结果。 You can " solve " the issue with: 您可以通过以下方式“ 解决 ”此问题:

x = re.sub(r'width="[0-9]{2,4}"','width="400"',x)
x = re.sub(r'height="[0-9]{2,4}"','height="400"',x)

That being said it is a very bad idea to process HTML/XML with regexes . 据说用正则表达式处理HTML / XML是一个非常糟糕的主意 Say you have a tag <foo altwidth="1234"> . 假设您有一个标签<foo altwidth="1234"> Now you will change it to <foo altwidth="400"> do you want that? 现在你将它改为<foo altwidth="400">你想要吗? Probably not. 可能不是。

You can for instance use BeautifulSoup : 例如,你可以使用BeautifulSoup

soup = BeautifulSoup(x,'lxml')

for tag in soup.findAll(attrs={"width":True})
    tag.width = 400
for tag in soup.findAll(attrs={"height":True})
    tag.height = 400
x = str(soup)

Here we substitute all tags with a width attribute to width="400" and all tags with a height with height="400" . 在这里,我们将所有 width属性的标签替换为width="400" ,所有标签的height height="400" You can make it more advanced by for instance only accepting <img> tags , like: 您可以通过例如仅接受<img>标签使其更高级,例如:

soup = BeautifulSoup(x,'lxml')

for tag in soup.findAll('img',attrs={"width":True})
    tag.width = 400
for tag in soup.findAll('img',attrs={"height":True})
    tag.height = 400
x = str(soup)

Seems to be working fine: 似乎工作正常:

>>> x = '<foo width="150" height="108">'
>>> import re
>>> y = re.sub(r'width="[0-9]{2,4}"','width="400"',x)
>>> y
'<foo width="400" height="108">'

Note that re.sub does not mutate x: 请注意, re.sub不会改变x:

>>> x
'<foo width="150" height="108">'
>>> y
'<foo width="400" height="108">'

Perhaps you want to do this instead: 也许你想这样做:

x = re.sub(r'width="[0-9]{2,4}"','width="400"',x)
x = re.sub(r'height="[0-9]{2,4}"','height="400"',x)

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