Question

我的文件包含以下行：

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，我想得到[Switch 1: 1.0]）

为此，我有这种模式：(\[Switch .*\])。
这是我正在使用的代码（的一部分）：

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)

整件事导致崩溃：

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]

因此该线不匹配我还检查了regex101。它似乎在那里工作.. Here is a link to it。

出了什么问题？
感谢

Answer 1

如果模式不在行的开头，则需要使用搜索，匹配将失败，除非模式位于行的开头：

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)

另一个正则表达式问题

1 个答案: