[英]Python and re.compile return inconsistent results
I'm trying to replace all instances of href="../directory"
with href="../directory/index.html"
. 我正在尝试将
href="../directory"
所有实例替换为href="../directory/index.html"
。
In Python, this 在Python中,
reg = re.compile(r'<a href="../(.*?)">')
for match in re.findall(reg, input_html):
output_html = input_html.replace(match, match+'index.html')
produces the following output: 产生以下输出:
href="../personal-autonomy/index.htmlindex.htmlindex.htmlindex.html"
href="../paternalism/index.html"
href="../principle-beneficence/index.htmlindex.htmlindex.html"
href="../decision-capacity/index.htmlindex.htmlindex.html"
Any idea why it works with the second link, but the others don't? 知道为什么它可以与第二个链接一起使用,但其他链接却不起作用吗?
Relevant part of the source: 来源的相关部分:
<p>
<a href="../personal-autonomy/">autonomy: personal</a> |
<a href="../principle-beneficence/">beneficence, principle of</a> |
<a href="../decision-capacity/">decision-making capacity</a> |
<a href="../legal-obligation/">legal obligation and authority</a> |
<a href="../paternalism/">paternalism</a> |
<a href="../identity-personal/">personal identity</a> |
<a href="../identity-ethics/">personal identity: and ethics</a> |
<a href="../respect/">respect</a> |
<a href="../well-being/">well-being</a>
</p>
EDIT : The repeated 'index.html' is actually the result of multiple matches. 编辑 :重复的'index.html'实际上是多个匹配项的结果。 (eg href="../personal-autonomy/index.htmlindex.htmlindex.htmlindex.html" is because ../personal-autonomy is found four times in the original source).
(例如href =“ ../ personal-autonomy / index.htmlindex.htmlindex.htmlindex.html”是因为在原始源中四次发现../personal-autonomy)。
As a general regex question, how would you replace all instances without adding an additional 'index.html' to all matches? 作为一般的正则表达式问题,如何在不向所有匹配项添加额外的“ index.html”的情况下替换所有实例?
Don't parse html with regexs: 不要用正则表达式解析html:
import re
from lxml import html
def replace_link(link):
if re.match(r"\.\./[^/]+/$", link):
link += "index.html"
return link
print html.rewrite_links(your_html_text, replace_link)
<p>
<a href="../personal-autonomy/index.html">autonomy: personal</a> |
<a href="../principle-beneficence/index.html">beneficence, principle of</a> |
<a href="../decision-capacity/index.html">decision-making capacity</a> |
<a href="../legal-obligation/index.html">legal obligation and authority</a> |
<a href="../paternalism/index.html">paternalism</a> |
<a href="../identity-personal/index.html">personal identity</a> |
<a href="../identity-ethics/index.html">personal identity: and ethics</a> |
<a href="../respect/index.html">respect</a> |
<a href="../well-being/index.html">well-being</a>
</p>
I think i found out the problem 我想我发现了问题
reg = re.compile(r'<a href="../(.*?)">')
for match in re.findall(reg, input_html):
output_html = input_html.replace(match, match+'index.html')
Here 'input_html' is modified inside the for loop and then same 'input_html' is searched again for the regex which is the bug :) 在这里,'input_html'在for循环中被修改,然后再次在同一个'input_html'中搜索正则表达式,这是一个bug :)
The problem is the content of the a-tag also matches what you try to replace. 问题是,a标签的内容也与您尝试替换的内容匹配。
It's in no way the ideal way to do it, but I think you will find it works correctly if you replace your regex with: 这绝不是理想的方法,但是我认为,如果将regex替换为:
reg = re.compile(r'<a href="(\.\./.*?)">')
There is an error in your regex in that the ..
does not match two dots. 正则表达式中有一个错误,因为
..
不匹配两个点。 Instead, it is the .
相反,它是
.
metacharacter . 元字符 。 To mean a dot, you need to escape it.
要表示一个点,您需要将其转义。
Your regex should be: <a href="\\.\\./(.*?)"
您的正则表达式应为:
<a href="\\.\\./(.*?)"
Besides, assuming all your href are of the form ../somedirectory/ you can get away with a simpler regex: 此外,假设所有您的href的形式为../somedirectory/你可以逃脱一个简单的正则表达式:
for match in re.compile(r'<a href="(.*?)"').findall(html):
html = html.replace(match, match + "index.html")
Here, the regex matches 在这里,正则表达式匹配
<a href=" # start of the taf and attribute
( # start of a group
.* # any character, any number of times
) # end of group
" # end of the attribute
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