Python 正则表达式重新编译说明

Question

所以我对以下代码有疑问:

def OnChanMsg(self, nick, channel, message):
        if 'Username' in nick.GetNick():
            stripped = message.s.strip() #strips leading and lagging whitespaces
            regex = re.compile("\x1f|\x02|\x12|\x0f|\x16|\x03(?:\d{1,2}(?:,\d{1,2})?)?", re.UNICODE) #recompiles the mesasge minus colorcodes, bold etc
            ircstripped = regex.sub("", stripped) 
            all = re.findall(r'test\ for\ (.*)\: ->\ (.*)\ \((.*)\)\ -\ \((.*)\)\ - \((.*)\).*', ircstripped)

所以我的问题如下:1)除了 "(?:\d{1,2}(?:,\d{1,2})?)?"之外，代码的作用对我来说相对清楚部分，我只是不明白它的作用和工作原理，我确实检查了谷歌开发人员codeschool视频，我还检查了python文档，但是当我的目标是去除IRC消息的颜色和其他各种格式时用(如果可能的话)外行人的话来说，这部分到底做了什么。

我在线程中发现了这个: How to strip color codes used by mIRC users?

(?: ... ) says to forget about storing what was found in the parenthesis (as we don't need to backreference it), ? means to match 0 or 1 and {n,m} means to match n to m of the previous grouping. Finally, \d means to match [0-9].

但我并没有真正明白=/

Answer 1

http://myregextester.com来救援!

NODE                     EXPLANATION
----------------------------------------------------------------------
(?-imsx:                 group, but do not capture (case-sensitive)
                         (with ^ and $ matching normally) (with . not
                         matching \n) (matching whitespace and #
                         normally):
----------------------------------------------------------------------
  (?:                      group, but do not capture (optional
                           (matching the most amount possible)):
----------------------------------------------------------------------
    \d{1,2}                  digits (0-9) (between 1 and 2 times
                             (matching the most amount possible))
----------------------------------------------------------------------
    (?:                      group, but do not capture (optional
                             (matching the most amount possible)):
----------------------------------------------------------------------
      ,                        ','
----------------------------------------------------------------------
      \d{1,2}                  digits (0-9) (between 1 and 2 times
                               (matching the most amount possible))
----------------------------------------------------------------------
    )?                       end of grouping
----------------------------------------------------------------------
  )?                       end of grouping
----------------------------------------------------------------------
)                        end of grouping
----------------------------------------------------------------------

因此，换句话说:可以选择捕获 1-2 位数字，也可以选择后跟由逗号和 1-2 位数字组成的组。

因此以下内容将匹配(假设全行匹配):

12
1
20
10,2
22,3
12,0
14,20

但以下不会:

200
a,b
!123p9
1000,2000