Python正则表达式多次匹配
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Python regex to match multiple times
提问by mavili
I'm trying to match a pattern against strings that could have multiple instances of the pattern. I need every instance separately. re.findall()shoulddo it but I don't know what I'm doing wrong.
我正在尝试将模式与可能具有该模式的多个实例的字符串进行匹配。我需要单独的每个实例。re.findall()应该这样做，但我不知道我做错了什么。
pattern = re.compile('/review: (http://url.com/(\d+)\s?)+/', re.IGNORECASE)
match = pattern.findall('this is the message. review: http://url.com/123 http://url.com/456')
I need 'http://url.com/123', http://url.com/456and the two numbers 123 & 456 to be different elements of the matchlist.
我需要“ http://url.com/123”，http://url.com/456和两个数123 456是不同的元素match列表。
I have also tried '/review: ((http://url.com/(\d+)\s?)+)/'as the pattern, but no luck.
我也试过'/review: ((http://url.com/(\d+)\s?)+)/'这种模式，但没有运气。
采纳答案by Narendra Yadala
Use this. You need to place 'review' outside the capturing group to achieve the desired result.
用这个。您需要将“”放在捕获组之外以达到预期的结果。
pattern = re.compile(r'(?:review: )?(http://url.com/(\d+))\s?', re.IGNORECASE)
This gives output
这给出了输出
>>> match = pattern.findall('this is the message. review: http://url.com/123 http://url.com/456')
>>> match
[('http://url.com/123', '123'), ('http://url.com/456', '456')]
回答by John Montgomery
You've got extra /'s in the regex. In python the pattern should just be a string. e.g. instead of this:
您在正则表达式中有额外的 / 。在python中，模式应该只是一个字符串。例如，而不是这个：
pattern = re.compile('/review: (http://url.com/(\d+)\s?)+/', re.IGNORECASE)
It should be:
它应该是：
pattern = re.compile('review: (http://url.com/(\d+)\s?)+', re.IGNORECASE)
Also typically in python you'd actually use a "raw" string like this:
通常在 python 中，您实际上会使用这样的“原始”字符串：
pattern = re.compile(r'review: (http://url.com/(\d+)\s?)+', re.IGNORECASE)
The extra r on the front of the string saves you from having to do lots of backslash escaping etc.
字符串前面的额外 r 使您不必进行大量反斜杠转义等。
回答by til_b
Use a two-step approach: First get everything from "review:" to EOL, then tokenize that.
使用两步法：首先获取从“评论：”到 EOL 的所有内容，然后对其进行标记。
msg = 'this is the message. review: http://url.com/123 http://url.com/456'
review_pattern = re.compile('.*review: (.*)$')
urls = review_pattern.findall(msg)[0]
url_pattern = re.compile("(http://url.com/(\d+))")
url_pattern.findall(urls)
