python3-基础11

 

##什么是正则
'''
正则就是用一些具有特殊含义的符号组合到一起（称为正则表达式）来描述字符或者字符
串的方法。或者说：正则就是用来描述一类事物的规则。（在Python中）它内嵌在Python中，
并通过 re 模块实现。正则表达式模式被编译成一系列的字节码，然后由用 C 编写的匹配引
擎执行.
'''

   

 

 

import re
# print(re.findall('\w','hello_ | egon 123'))  #匹配字母数字下划线，单个字符进行匹配
# print(re.findall('\W','hello_ | egon 123'))  #匹配非字母数字下划线
# print(re.findall('\s','hello_ | egon 123 \n \t'))
# print(re.findall('\S','hello_ | egon 123 \n \t'))
# print(re.findall('\d','hello_ | egon 123 \n \t'))
# print(re.findall('\D','hello_ | egon 123 \n \t'))
# print(re.findall('h','hello_ | hello h egon 123 \n \t'))
# # print(re.findall('\Ahe','hello_ | hello h egon 123 \n \t'))
# print(re.findall('^he','hello_ | hello h egon 123 \n \t'))
# # print(re.findall('123\Z','hello_ | hello h egon 123 \n \t123'))
# print(re.findall('123$','hello_ | hello h egon 123 \n \t123'))
# print(re.findall('\n','hello_ | hello h egon 123 \n \t123'))
# print(re.findall('\t','hello_ | hello h egon 123 \n \t123'))

['h', 'e', 'l', 'l', 'o', '_', 'e', 'g', 'o', 'n', '1', '2', '3']
[' ', '|', ' ', ' ']
[' ', ' ', ' ', ' ', '\n', ' ', '\t']
['h', 'e', 'l', 'l', 'o', '_', '|', 'e', 'g', 'o', 'n', '1', '2', '3']
['1', '2', '3']
['h', 'e', 'l', 'l', 'o', '_', ' ', '|', ' ', 'e', 'g', 'o', 'n', ' ', ' ', '\n', ' ', '\t']
['h', 'h', 'h']
['he']
['he']
['123']
['123']
['\n']
['\t']

　　

#. [] [^] #.本身代表任意一个字符 
# print(re.findall('a.c','a a1c a*c a2c abc a c aaaaaac aacc')) 
#a.c 
# print(re.findall('a.c','a a1c a*c a2c abc a\nc',re.DOTALL)) 
# print(re.findall('a.c','a a1c a*c a2c abc a\nc',re.S)) 
#[]内部可以有多个字符，但是本身只配多个字符中的一个 
# print(re.findall('a[0-9][0-9]c','a a12c a1c a*c a2c a c a\nc',re.S)) 
# print(re.findall('a[a-zA-Z]c','aac abc aAc a12c a1c a*c a2c a c a\nc',re.S))
# print(re.findall('a[^a-zA-Z]c','aac abc aAc a12c a1c a*c a2c a c a\nc',re.S)) 
# print(re.findall('a[\+\/\*\-]c','a-c a+c a/c aac abc aAc a12c a1c a*c a2c a c a\nc',re.S)) 

['a12c']
['aac', 'abc', 'aAc']
['a1c', 'a*c', 'a2c', 'a c', 'a\nc']
['a-c', 'a+c', 'a/c', 'a*c']

#\:转义 
# print(re.findall(r'a\\c','a\c abc')) #rawstring 
#? * + {}：左边有几个字符，如果有的话，贪婪匹配 
#?左边那一个字符有0个或者1个 # print(re.findall('ab?','aab a ab aaaa')) #ab? 
#*左边那一个字符有0个或者无穷个 
# print(re.findall('ab*','a ab abb abbb abbbb bbbbbb')) 
# print(re.findall('ab{0,}','a ab abb abbb abbbb bbbbbb')) 

['a', 'ab', 'abb', 'abbb', 'abbbb']
['a', 'ab', 'abb', 'abbb', 'abbbb']

#+左边那一个字符有1个或者无穷个 
# print(re.findall('ab+','a ab abb abbb abbbb bbbbbb')) 
# print(re.findall('ab{1,}','a ab abb abbb abbbb bbbbbb')) #{n,m}左边的字符有n-m次 
# print(re.findall('ab{3}','a ab abb abbb abbbb bbbbbb')) 
# print(re.findall('ab{2,3}','a ab abb abbb abbbb bbbbbb')) # .* .*? 

['ab', 'abb', 'abbb', 'abbbb']
['ab', 'abb', 'abbb', 'abbbb']
['abbb', 'abbb']
['abb', 'abbb', 'abbb']

#.*贪婪匹配 找最多的 # print(re.findall('a.*c','a123c456c')) 
#.*?非贪婪匹配 # print(re.findall('a.*?c','a123c456c')) #| 或者 任意批配  
# print(re.findall('company|companies','Too many companies have gone bankrupt, and the next one is my company')) 
                                              # company|companies 
# print(re.findall('compan|companies','Too many companies have gone bankrupt, and the next one is my company')) 

['companies', 'company']
['compan', 'compan']

#():分组 
# print(re.findall('ab+','abababab123')) 
# print(re.findall('ab+123','abababab123')) 

['ab', 'ab', 'ab', 'ab']
['ab123']

# print(re.findall('ab','abababab123'))
# print(re.findall('(ab)','abababab123'))
# print(re.findall('(a)b','abababab123'))
# print(re.findall('a(b)','abababab123'))
# print(re.findall('(ab)+','abababab123'))
# print(re.findall('(?:ab)+','abababab123'))  #？： 匹配完整词语

['ab', 'ab', 'ab', 'ab']
['ab', 'ab', 'ab', 'ab']
['a', 'a', 'a', 'a']
['b', 'b', 'b', 'b']
['ab']
['abababab']

# print(re.findall('(ab)+123','abababab123'))
# print(re.findall('(?:ab)+123','abababab123'))
# print(re.findall('(ab)+(123)','abababab123'))

['ab']
['abababab123']
[('ab', '123')]

# print(re.findall('compan(y|ies)','Too many companies have gone bankrupt, and the next one is my company'))
# print(re.findall('compan(?:y|ies)','Too many companies have gone bankrupt, and the next one is my company'))

['ies', 'y']
['companies', 'company']

#re的其他方法 search 找成功一次就结束  match 从头开始是匹配
# print(re.findall('ab','abababab123'))
# print(re.search('ab','abababab123').group())
# print(re.search('ab','12aasssdddssssssss3'))
# print(re.search('ab','12aasssdddsssssssab3sssssss').group())

['ab', 'ab', 'ab', 'ab']
ab
None
ab

# print(re.search('ab','123ab456'))
# print(re.match('ab','123ab456')) 
# print(re.search('^ab','123ab456'))

# split 切分
# print(re.split('b','abcde'))
# print(re.split('[ab]','abcde'))  

# sub 替换
# print(re.sub('alex','SB','alex make love alex alex',1))   #1是替换一次，也可不用该参数
# print(re.subn('alex','SB','alex make love alex alex',1))  #显示替换几次
# print(re.sub('(\w+)(\W+)(\w+)(\W+)(\w+)',r'\5\2\3\4\1','alex make love')) #\w 匹配单词  \W 匹配非单词 12345 代表匹配的组
# print(re.sub('(\w+)( .* )(\w+)',r'\3\2\1','alex make love'))

# obj=re.compile('\d{2}')  #定义一个正则表达式，数字出现两次
# print(obj.search('abc123eeee').group()) #12
# print(obj.findall('abc123eeee')) #12

<_sre.SRE_Match object; span=(3, 5), match='ab'>
None
None
['a', 'cde']
['', '', 'cde']
SB make love alex alex
('SB make love alex alex', 1)
love make alex
love make alex
12
['12']

print(re.findall('\-?\d+\.?\d+',"1-12*(60+(-40.35/5)-(-4*3))"))
print(re.findall('\-?\d+\.?\d*',"1-12*(60+(-40.35/5)-(-4*3))"))

# print(re.findall('\-?\d+\.\d+',"1-12*(60+(-40.35/5)-(-4*3))"))
# print(re.findall('\-?\d+',"1-12*(60+(-40.35/5)-(-4*3))"))

# print(re.findall('\-?\d+\.\d+|(\-?\d+)',"1-12*(60+(-40.35/5)-(-4*3))"))
# print(re.findall('\-?\d+\.\d+|\-?\d+',"1-12*(60+(-40.35/5)-(-4*3))"))
# print(re.findall('\-?\d+|\-?\d+\.\d+',"1-12*(60+(-40.35/5)-(-4*3))"))

['-12', '60', '-40.35']
['1', '-12', '60', '-40.35', '5', '-4', '3']
['-40.35']
['1', '-12', '60', '-40', '35', '5', '-4', '3']
['1', '-12', '60', '', '5', '-4', '3']
['1', '-12', '60', '-40.35', '5', '-4', '3']
['1', '-12', '60', '-40', '35', '5', '-4', '3']