Python 不允许我用正则表达式做 match.group()？

Question

我用 Python 编写了一个正则表达式来从字符串中获取数字。但是，当我运行 match.group() 时，它说对象 list 没有属性 group。我究竟做错了什么？我输入的代码粘贴到终端，以及终端的响应。谢谢。

>>> #import regex library
... import re
>>> 
>>> #use a regex to just get the numbers -- not the rest of the string
... matcht = re.findall(r'\d', dwtunl)
>>> matchb = re.findall(r'\d', ambaas)
>>> #macht = re.search(r'\d\d', dwtunl)
... 
>>> #just a test to see about my regex
... print matcht.group()
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
AttributeError: 'list' object has no attribute 'group'
>>> print matchb.group()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'group'
>>> 
>>> #start defining the final variables
... if dwtunl == "No Delay":
...     dwtunnl = 10
... else:
...     dwtunnl = matcht.group()
... 
Traceback (most recent call last):
  File "<stdin>", line 5, in <module>
AttributeError: 'list' object has no attribute 'group'
>>> if ambaas == "No Delay":
...     ammbaas = 10
... else:
...     ammbaas = matchb.group()
... 
Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
AttributeError: 'list' object has no attribute 'group'

Answer 1

re.findall() 不返回匹配对象(或它们的列表)，它总是返回字符串列表(或字符串元组列表，如果是有不止一个捕获组)。并且列表没有 .group() 方法。

>>> import re
>>> regex = re.compile(r"(\w)(\W)")
>>> regex.findall("A/1$5&")
[('A', '/'), ('1', '$'), ('5', '&')]

re.finditer() 将返回一个迭代器，每次匹配产生一个匹配对象。

>>> for match in regex.finditer("A/1$5&"):
...     print match.group(1), match.group(2)
...
A /
1 $
5 &