The backslash works:
To treat a metacharacter ^ as a normal character, add the backslash
Example:
>>>import re >>>r=r'\^abc' >>>(r,'^abc ^abc ^abc') ['^abc','^abc','^abc']
\d matches any decimal number, it is equivalent to class [0-9].
\D matches any non-numeric character, it is equivalent to class [^0-9]
\s matches any blank character, he is equivalent to the class [\t\n\r\f\v]
\S matches any non-whitespace character, it is equivalent to the class [^\t\n\r\f\v]
\w matches any alphanumeric character, it is equivalent to the class [a-zA-Z0-9_]
\W matches any non-alphanumeric character, it is equivalent to class [^a-zA-Z0-9_]
>>>r=r'[0-9]' >>>(r,'1234567890') ['1','2','3','4','5','6','7','8','9','0'] >>>r=r'\d' >>>(r,'1234567890') ['1','2','3','4','5','6','7','8','9','0']
>>>r=r'^010-\d\d\d\d\d\d\d\d'
>>>(r,'010-87654321')
['010-87654321']
>>>(r,'010-8765432')
[]
>>>r=r'^010-\d{8}'#Repeat eight times
>>>(r,'010-12345678')
['^010-12345678']
Role of asterisks: (*)
Matches a preceding character zero or more times.
>>>r=r'ab*' >>>(r,'a') ['a'] >>>(r,'ab') ['ab'] >>>(r,'abbbbbb') ['abbbbbb']
Function of the plus sign: (+)
Indicates one or more matches.
>>>r=r'ab+' >>>(r,'a') [] >>>(r,'ab') ['ab'] >>>(r,'abbbb') ['abbbb']
Problem of "-" in the middle of telephone numbers: (optional)
>>>r=r'^010-*\d{8}'
>>>(r,'010-12345678')
['010-12345678']
>>>(r,'01012345678')
['01012345678']
>>>(r,'010---12345678')
['010---12345678']
The role of question marks: (?)
Match once or zero times;
>>>r=r'^010-?\d{8}$'
>>>(r,'010--12345678')
[]
>>>(r,'010-12345678')
['010-12345678']
>>>(r,'01012345678')
['01012345678']
Do minimal pattern matching:
Greedy pattern matching is as follows:
>>>r=r'ab+' >>>(r,'abbbbbbbbbbb') ['abbbbbbbbbbb']
Non-greedy pattern matching with a question mark as a minimum match is as follows:
>>>r=r'ab+?' >>>(r,'abbbbbbbbbbb') ['ab'] >>>r=r'ab*?' >>>(r,'abbbbbbbbbbbb') ['a']
Usage of parentheses: (｛m,n｝)
where m and n are decimal integers. The qualifier means that there are at least m repetitions and at most n repetitions.
>>>r=r'a{1,3}'# indicates that a is repeated one to three times
>>>(r,'a')
['a']
>>>(r,'aa')
['aa']
>>>(r,'aaa')
['aaa']
>>>(r,'aaaa')
['aaa','a']
Grouping: "(" and ")"
>>> import re
>>> email=r'\w{3}@\w+(\.com|\.cn)'# Define regular, (\.com|\.cn) represents a grouping; do ** or ** operations in the grouping, either .com, or .cn
>>> (email,'www@')# Make a match
<_sre.SRE_Match object; span=(0, 13), match='www@'>
>>> (email,'www@')
<_sre.SRE_Match object; span=(0, 12), match='www@'>
>>> (email,'www@')
>>> # Returns the null value
>>> (email,'www@')
['.com'] # Doing a match prioritizes the return of data in the grouping
>>> (email,'www@')
['.cn']
>>>
>>> s=''' ajhfa kasjf owolf english=chinese yes no print lafl int=456 yes float int=789 yes owolf english=france yes aklfl '''#Define String >>> r=r'owolf english=.+ yes' #define regular >>> (r,s) #MatchRegular ['owolf english=chinese yes', 'owolf english=france yes'] >>> r=r'owolf english=(.+) yes' >>> (r,s) ['chinese', 'france'] #Using grouping to prioritize the return of data in groups，Often used in crawlers
summarize
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