Python正则表达式教程

1、import re1查找第一个匹配用s = 'i love python very much' pat = 'python'r = re.search(pat,s) print(r.span() #(7,13)2查找所有1s =''pat = '1'r = re.finditer(pat,s)for i in r: print(i)# <re.Match object; span=(9, 10), match='1'># <re.Match object; span=(14, 15), match

2、='1'>3 d匹配数字0-9s ='一共20行代码运行时间13.59s'pat = r'd+' # +表示匹配数字(d表示数字的通用字符)1次或多次r = re.findall(pat,s)print(r)#'20', '13', '59'我们想保留13. 59而不是分开，请看44 ?表示前一个字符匹配0或1次s ='一共20行代码运行时间13.59s'pat = r'd+.?d+' #“示匹配小数点(.)0次或1次 r = re.findall(pat,s)

3、print(r)#'20', '13.59'5 A匹配字符串的开头s = 'This module provides regular expression matching operations similar to those fou nd in Perl'pat = r'Aemrt' # 查找以r = re.findall(pat,s)print(r)# ,因为字符串的开头是字符'，不在emrt匹配范围内，所以返回为空 6 re.I忽略大小写 s = 'This module provides regular

4、expression matching operations similar to those fou nd in Perl'pat = r'Aemrt' # 查找以r = pile(pat,re.I).search(s)print(r)# <re.Match object; span=(0, 1), match='T'>表明字符串的开头在匹配列表中7使用正则提取单词这是不准确版本，请参看第9个s = 'This module provides regular expression matching operations simila

5、r to those fou nd in Perl'pat = r'sa-zA-Z+'r = re.findall(pat,s)print(r) #' module', ' provides', ' regular', ' expression', ' matching', ' operations', ' simil ar', ' to', ' those', ' found', ' in',

6、' Perl'8只捕获单词，去掉空格使用()捕获，这是不准确版本，请参看第9个s = 'This module provides regular expression matching operations similar to those fou nd in Perl'pat = r's(a-zA-Z+)'r = re.findall(pat,s)print(r) #'module', 'provides', 'regular', 'expression', 'matchi

7、ng', 'operations', 'similar',' to', 'those', 'found', 'in', 'Perl'9补充上第一个单词上面第8,看到提取单词中未包括第一个单词，使用？表示前面字符出现0次或1次，但是此字符还有表示贪心或非贪心匹配含义，使用时 要谨慎。s = 'This module provides regular expression matching operations similar to those fou nd in Per

8、l'pat = r's?(a-zA-Z+)'r = re.findall(pat,s)print(r) #'This', 'module', 'provides', 'regular', 'expression', 'matching', 'operations', 'si milar', 'to', 'those', 'found', 'in', 'Perl'10

9、使用spl it函数直接分割单词使用以上方法分割单词，不是简洁的，仅仅为了演示。分割单词最简 单还是使用spl it函数。s = 'This module provides regular expression matching operations similar to those fou nd in Perl'pat = r's+'r = re.split(pat,s)print(r) # 'This', 'module', 'provides', 'regular', 'express

10、ion', 'matching', 'operations', 'si milar', 'to', 'those', 'found', 'in', 'Perl'11提取以m或t开头的单词，忽略大小写 下面出现的结果不是我们想要的，原因出在？上！ s = 'This module provides regular expression matching operations similar to those fou nd in Perl'pat

11、= r's?(mta-zA-Z*)' # 查找以 r = re.findall(pat,s)print(r) # 'module', 'matching', 'tions', 'milar', 'to', 'those' 12使用A查找字符串开头的单词综合11和12得到所有以m或t开头的单词s = 'This module provides regular expression matching operations similar to those fou nd in Pe

12、rl'pat = r'A(mta-zA-Z*)s' # 查找以 r = pile(pat,re.I).findall(s) print(r) # 'This'13先分割，再查找满足要求的单词 使用match表示是否匹配s = 'This module provides regular expression matching operations similar to those fou nd in Perl'pat = r's+' r = re.split(pat,s)res = i for i in r if re.ma

13、tch(r'mMtT,i)print(res) # 'This', 'module', 'matching', 'to', 'those' 14贪心匹配尽可能多的匹配字符content='<h>ddedadsad</h><div>graph</div>bb<div>math</div>cc' pat=pile(r"<div>(.*)</div>") # 贪婪模式m=pat.fi

14、ndall(content)print(m) # 'graph</div>bb<div>math'1 5非贪心匹配与14相比，仅仅多了 一个问号(？)，得到结果完全不同。content='<h>ddedadsad</h><div>graph</div>bb<div>math</div>cc' pat=pile(r"<div>(.*?)</div>") # 贪婪模式m=pat.findall(content) print(m)

15、 # 'graph', 'math'与14比较可知，贪心匹配和非贪心匹配的区别，后者是字符串匹配后 立即返回，见好就收。16含有多种分割符使用spl it函数content = 'graph math,english;chemistry'钻种 pat=pile(r"s,;+") # 贪婪模式m=pat.split(content)print(m) # 'graph', 'math', 'english', 'chemistry' 17替换匹配的子用sub函数实现对匹配子用的替换content="hello 12345, hello 456321"pat=pile(r'd+')艘替换的部分m=pat.sub("666",content)print(m) # hello 666, hello 66619常用元