Python re module

Re module common methods:

ImportReret= Re.findall ('a','Eva Egon Yuan')#returns all results that meet the matching criteria, placed in the list,#Re.findall (' Regular expression ', ' Match string ') returns the string that satisfies the expression in the string to be matchedPrint(ret)#result: [' A ', ' a ']ret= Re.search ('a','Eva Egon Yuan'). Group ()#The search method finds the first string within a string that satisfies the expression and returns a regular object address#to view the returned content through group (), no match succeeded String returned nonePrint(ret)#result: ' A '#The function finds a pattern match within the string, only to find the first match and then returns an object that contains the matching information that can be#a matching string is obtained by calling the group () method, and none is returned if the string does not match. ret= Re.match ('a','ABC'). Group ()#with search, but only at the beginning of the string, start out a string that does not match the expression, return none,#If the match succeeds, the returned string is viewed by group ()Print(ret)#result: ' A 'ret= Re.split ('[AB]','ABCD')#first Press ' a ' to split the ' and ' BCD ', in the pair ' and ' BCD ' separate by ' B 'Print(ret)#[', ', ', ' CD ']ret= Re.sub ('\d','H','Eva3egon4yuan4', 1)#replace number with ' H ', parameter 1 means replace only 1Print(ret)#Evahegon4yuan4ret= Re.subn ('\d','H','Eva3egon4yuan4')#replace the number with ' H ', return the tuple (replace the result, replace the number of times)Print(ret)#results: (' Evahegonhyuanh ', 3)obj= Re.compile ('\d{3}')#compiles a regular expression into a regular expression object, with the rule matching 3 digitsret = Obj.search ('abc123eeee')#The regular Expression object calls search, and the argument is the string to be matchedPrint(Ret.group ())#results: 123ImportReret= Re.finditer ('\d','ds3sy4784a')#Finditer Returns an iterator that holds the matching resultPrint(ret)#<callable_iterator object at 0x10195f940>Print(Next (Ret). Group ())#View the first resultPrint(Next (Ret). Group ())#View the second result#for I in RET: #可以对迭代器进行迭代, view each content#print (I.group ())Print([I.group () forIinchRET])#view remaining left and right results

Attention:

1. FindAll's priority query: '?: ' returns the match for cancellation priority

ImportReret= Re.findall ('www. (baidu|oldboy). com','www.oldboy.com')Print(ret)#[' Oldboy '] This is because FindAll will prioritize the contents of the matching results group, and if you want to match the results, cancel the permissionsret= Re.findall ('www. (?: baidu|oldboy). com','www.oldboy.com')Print(ret)#[' www.oldboy.com ']

2. Split's priority query:

Ret=re.split ("\d+","Eva3egon4yuan")Print(ret)#results: [' Eva ', ' Egon ', ' Yuan ']ret=re.split ("(\d+)","Eva3egon4yuan")Print(ret)#results: [' Eva ', ' 3 ', ' Egon ', ' 4 ', ' Yuan ']#after the matching section plus () The result is different,#There is no reservation for the matching item, but there is a () to keep the matching item .#This is very important in some of the use processes that need to keep the matching part. 

Cases:

Group naming:

(? p<name> regular expression), indicating the name of the group

(? P = name) indicates the use of this grouping, where the match should be exactly the same as the content in the group

Python re module