python - 在下一个方法中使用正则表达式和捕获组 [英] python - using regex and capture groups in next method

问题描述

我需要这方面的帮助:

1. 我打开文件，使用 readlines 方法从中创建一个列表.

2. 我需要找到第一次出现的模式/匹配并将第一个捕获组分配给变量

1. I open file, use readlines method to create a list out of it.

2. I need to find first occurrence of patern/match and assign first capture group to variable

list = ['firstString','xxxSTATUS=100','thirdString','fourthString']
value = next(x for x in list if [re.search('.*STATUS=(.*)', x)])

如果我按原样将它分配给值"，我会得到xxxSTATUS=100"(字符串类型)，但如果我这样做:

if I assign it to 'value' as it is, I get 'xxxSTATUS=100' (string type), BUT if I do it like so:

  value = next(x for x in list if [re.search('.*STATUS=(.*)', x).group(1)])

我明白了:

AttributeError: 'NoneType' 对象没有属性 'group'

AttributeError: 'NoneType' object has no attribute 'group'

显然我不能做 value.group(1) 因为它是字符串而不是正则表达式对象.我也得到(这是我的假设)，在我使用正则表达式模式时，我的变量仍然没有类型，因为它尚未分配.

Obviously I can't do value.group(1) as it is string and not regex object. I also get (it is my assumption) that at the time I'm using regex pattern, my variable is still of no type,because it wasn't assigned yet.

所以我的问题是如何解决这个问题并分配捕获组，例如.'100' 到变量.有什么解决方法吗?

推荐答案

AttributeError: 'NoneType' object has no attribute 'group' 错误只是意味着您没有匹配项并尝试访问组内容一个空对象.

The AttributeError: 'NoneType' object has no attribute 'group' error just means you got no match and tried to access group contents of a null object.

我认为最简单的方法是遍历搜索匹配项的列表项，一旦找到，获取第 1 组内容并将它们分配给 value:

I think the easiest way is to iterate over the list items searching for the match, and once found, get Group 1 contents and assign them to value:

import re
list = ['firstString','xxxSTATUS=100','thirdString','fourthString']
value = ""
for x in list:
    m = re.search('STATUS=(.*)', x)
    if m:
        value = m.group(1)
        break

print(value)

注意你不需要模式中的初始 .* 因为 re.search 模式没有锚定在字符串的开头.

Note you do not need the initial .* in the pattern as re.search pattern is not anchored at the start of the string.

查看 Python 演示

另外，如果你想让你的初始方法起作用，你需要先检查是否有匹配 if re.search('STATUS=(.*)', x) 和然后再次运行它以使用 re.search('STATUS=(.*)', x).group(1):

Also, if you want your initial approach to work, you need to check if there is a match first with if re.search('STATUS=(.*)', x), and then run it again to get the group contents with re.search('STATUS=(.*)', x).group(1):

value = next(re.search('STATUS=(.*)', x).group(1) for x in list if re.search('STATUS=(.*)', x))

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