[英]Using regular expression to extract string
I need to extract the IP address from the following string. 我需要从以下字符串中提取IP地址。
>>> mydns='ec2-54-196-170-182.compute-1.amazonaws.com'
The text to the left of the dot needs to be returned. 需要返回点左侧的文本。 The following works as expected. 以下按预期工作。
>>> mydns[:18]
'ec2-54-196-170-182'
But it does not work in all cases. 但它并不适用于所有情况。 For eg 例如
mydns='ec2-666-777-888-999.compute-1.amazonaws.com'
>>> mydns[:18]
'ec2-666-777-888-99'
How to I use regular expressions in python? 如何在python中使用正则表达式?
No need for regex... Just use str.split
不需要正则表达式...只需使用str.split
mydns.split('.', 1)[0]
Demo: 演示:
>>> mydns='ec2-666-777-888-999.compute-1.amazonaws.com'
>>> mydns.split('.', 1)[0]
'ec2-666-777-888-999'
If you wanted to use regex for this: 如果你想使用正则表达式:
ec2-([0-9]{1,3})-([0-9]{1,3})-([0-9]{1,3})-([0-9]{1,3}).*
Alternative (EC2 Agnostic): 替代方案(EC2 Agnostic):
.*\\b([0-9]{1,3})-([0-9]{1,3})-([0-9]{1,3})-([0-9]{1,3}).*
Regular: \\1.\\2.\\3.\\4
常规: \\1.\\2.\\3.\\4
Reverse: \\4.\\3.\\2.\\1
反转: \\4.\\3.\\2.\\1
import re
subject = 'ec2-54-196-170-182.compute-1.amazonaws.com'
result = re.sub("ec2-([0-9]{1,3})-([0-9]{1,3})-([0-9]{1,3})-([0-9]{1,3}).*", r"\1.\2.\3.\4", subject)
print result
This regex will match (^[^.]+
: 这个正则表达式将匹配(^[^.]+
:
So Try this: 试试这个:
import re
string = "ec2-54-196-170-182.compute-1.amazonaws.com"
ip = re.findall('^[^.]+',string)[0]
print ip
Output: 输出:
ec2-54-196-170-182
Best thing is this will match even if the instance was ec2
, ec3
so this regex is actually very much similar to the code of @mgilson 最好的事情是这将匹配,即使实例是ec2
, ec3
所以这个正则表达式实际上非常类似于@mgilson的代码
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