正则表达式（二）示例

首先创建用于正则表达式练习的数据生成器

from random import randrange,choice 
#randrange：在取值范围内按步长随机选择一个数(步长默认为1）
#choice：在序列中随机抽取一个元素
from string import ascii_lowercase as lc#字符串常量：小写字母’abcdefghijklmnopqrstuvwxyz’
from sys import maxsize
from time import ctime
import re
file = open('redata.txt','w')
tlds = ('com','edu','net','org','gov')
for i in range(randrange(5,11)):
    dtint = randrange(maxsize)
    dint = dtint//500000000
    dtstr = ctime(dint)
    llen = randrange(4,8)
    login = ''.join(choice(lc) for i in range(llen))
    dlen = randrange(llen,13)
    dom = ''.join(choice(lc) for i in range(dlen))
    new_str = dtstr + '::' + login + '@' + dom + '.' + choice(tlds) + '::' + str(dtint) + '-'  + str(llen)+ '-' + str(dlen)
    file.writelines(new_str + '\n')
file.close()

生成的redata.txt文件如图所示：

现在针对生成的数据进行正则表达式创建的练习：

1.提取每行中完整的时间戳

re_1 = '(\w{3}\s\w{3}\s\d{2}\s\d{2}\:\d{2}\:\d{2})'
file = open('redata.txt','r')
for i in file:
    print(re.search(re_1,i).group())

output:

Fri Jul 24 12:49:28
Sat Jul 13 14:56:27
Tue Jun 11 14:59:01
Sun Nov 16 23:35:12
Sun Aug 20 03:06:54
Thu Oct 22 19:22:44
Sun Dec 10 10:50:28
In [115]:

2.提取每行中完整的电子邮件地址

re_2 = '[A-Za-z]+\@[A-Za-z]+\.(?:(com)|(net)|(edu)|(org)|(gov))'
file = open('redata.txt','r')
for i in file:
    print(re.search(re_2,i).group())

output

jsqneel@sxmwmghgkklz.edu
lzkrgvw@evwbsxcne.net
lhrdg@etwxyphb.gov
xwonzk@utooardkqf.edu
xbwsxmx@hhgjuwev.com
hqkchi@pndjkbk.edu
pswzf@tcpeltvcvlp.gov

3.仅仅提取时间戳中的月份

re_3 = '\w{3}\s(\w{3})\s\d{2}'
file = open('redata.txt','r')
for i in file:
    print(re.search(re_3,i).groups())

output

('Jul',)
('Jul',)
('Jun',)
('Nov',)
('Aug',)
('Oct',)
('Dec',)

4.使用你的电子邮件地址替换每一行数据中的电子邮件地址

Way1

re_2 = '[A-Za-z]+\@[A-Za-z]+\.(?:(com)|(net)|(edu)|(org)|(gov))'
file = open('redata.txt','r')
email = []
for i in file:
    search_ans = re.search(re_2,i).group()
    begin = i.find(search_ans)
    length = len(search_ans)
    i = i[:begin]+'1137051592@qq.com'+i[begin+length:]

Way2

pattern = re.compile(r'\w*@\w*\.\w{3}') 
for i in file:
    print(pattern.sub('1137051592@qq.com',i))

output

Fri Jul 24 12:49:28 2465::1137051592@qq.com::7819208684208157264-7-12
Sat Jul 13 14:56:27 2211::1137051592@qq.com::3810943693690783132-7-9
Tue Jun 11 14:59:01 2368::1137051592@qq.com::6286822170785249237-5-8
Sun Nov 16 23:35:12 2273::1137051592@qq.com::4794709656073062452-6-10
Sun Aug 20 03:06:54 2484::1137051592@qq.com::8120165607099149502-7-8
Thu Oct 22 19:22:44 2105::1137051592@qq.com::2142826882005325784-6-7
Sun Dec 10 10:50:28 2417::1137051592@qq.com::7067827514111045325-5-11

5.提取并捕获html标签内容

html标签，例：

<a href = 'www.google.com'>Content</a>

提取标签内容：

html = '<a href="www.google.com">Content</a>'
re_4 = '<(?:[^>]*)>([^<]+)</a>'
re.search(re_4,html).groups()

output

('Content',)

其中，[^>]表示匹配除’>'以外所有字符，‘?:'表示匹配但不获取匹配结果

注意： 要注意区分’/‘和’\’，其中转义符为’\’