python - 另一个正则表达式问题

Question

我有一个包含以下行的文件:

2015-08-11 13:31:06.609 CEST [SwitchEvent Thread] INFO  o.o.t.t.internal.learning.Learning - Probabilities for Host 1:  [Switch 1: 1.0]
2015-08-11 13:31:07.349 CEST [SwitchEvent Thread] INFO  o.o.t.t.internal.learning.Learning - Probabilities for Host 1:  [Switch 1: 0.5, Switch 2: 0.5]

我想得到它的最后一部分(例如，在第 1 行中，我想得到 [Switch 1: 1.0])

为此，我有这个模式:(\[Switch .*\])。
这是我正在使用的(部分)代码:

import os
import sys
import re

data_pattern = re.compile('(\[Switch .*\])')

f = open('some_file', 'r')
for line in f:
    print line
    data_match = data_pattern.match(line)
    print data_match.group(0)

整个事情导致崩溃:

Traceback (most recent call last):
  File "/home/nemo-develop/PycharmProjects/Affinity-Remote/learning_data_preparation.py", line 62, in <module>
    read_file(join(directory, filename), switch_amount)
  File "/home/nemo-develop/PycharmProjects/Affinity-Remote/learning_data_preparation.py", line 33, in read_file
    print data_match.group(0)
AttributeError: 'NoneType' object has no attribute 'group'
2015-08-11 13:31:06.609 CEST [SwitchEvent Thread] INFO  o.o.t.t.internal.learning.Learning - Probabilities for Host 1:  [Switch 1: 1.0]

所以行不匹配。
我还检查了 regex101。它似乎在那里工作.. Here is a link to it .

出了什么问题？
谢谢

Answer 1

如果模式不在行首，则需要使用搜索，除非模式在行首，否则匹配失败:

import re
data_pattern = re.compile(r'(\[Switch .*\])')

f = open('some_file', 'r')
for line in f:
    print line
    # CHANGE TO RE.SEARCH HERE:
    data_match = data_pattern.search(line)
    print data_match.group(0)