Python中正则表达式的用法实例汇总


            正则表达式是Python程序设计中非常实用的功能，本文就常用的正则表达式做一汇总，供大家参考之用。具体如下：

一、字符串替换

1.替换所有匹配的子串

用newstring替换subject中所有与正则表达式regex匹配的子串





result, number = re.subn(regex, newstring, subject)





2.替换所有匹配的子串（使用正则表达式对象）





reobj = re.compile(regex)

result, number = reobj.subn(newstring, subject)







二、字符串拆分

1.字符串拆分





result = re.split(regex, subject)





2.字符串拆分（使用正则表示式对象）





reobj = re.compile(regex)

result = reobj.split(subject)







三、匹配

下面列出Python正则表达式的几种匹配用法：

1.测试正则表达式是否匹配字符串的全部或部分





regex=ur"..." #正则表达式

if re.search(regex, subject):

  do_something()

else:

  do_anotherthing()





2.测试正则表达式是否匹配整个字符串





regex=ur"...\Z" #正则表达式末尾以\Z结束

if re.match(regex, subject):

  do_something()

else:

  do_anotherthing()





3. 创建一个匹配对象，然后通过该对象获得匹配细节





regex=ur"..." #正则表达式

match = re.search(regex, subject)

if match:

  # match start: match.start()

  # match end (exclusive): match.end()

  # matched text: match.group()

  do_something()

else:

  do_anotherthing()





4.获取正则表达式所匹配的子串





(Get the part of a string matched by the regex)



regex=ur"..." #正则表达式

match = re.search(regex, subject)

if match:

  result = match.group()

else:

  result = ""







5. 获取捕获组所匹配的子串





(Get the part of a string matched by a capturing group)



regex=ur"..." #正则表达式

match = re.search(regex, subject)

if match:

  result = match.group(1)

else:

  result = ""







6. 获取有名组所匹配的子串





(Get the part of a string matched by a named group)



regex=ur"..." #正则表达式

match = re.search(regex, subject)

if match:

  result = match.group("groupname")

else:

  result = ""







7. 将字符串中所有匹配的子串放入数组中





(Get an array of all regex matches in a string)



result = re.findall(regex, subject)







8.遍历所有匹配的子串





(Iterate over all matches in a string)



for match in re.finditer(r"<(.*?)\s*.*?/\1>", subject)

  # match start: match.start()

  # match end (exclusive): match.end()

  # matched text: match.group()







9.通过正则表达式字符串创建一个正则表达式对象





(Create an object to use the same regex for many operations)



reobj = re.compile(regex)







10.用法１的正则表达式对象版本





(use regex object for if/else branch whether (part of) a string can be matched)



reobj = re.compile(regex)

if reobj.search(subject):

  do_something()

else:

  do_anotherthing()







11.用法２的正则表达式对象版本





(use regex object for if/else branch whether a string can be matched entirely)



reobj = re.compile(r"\Z")　#正则表达式末尾以\Z 结束

if reobj.match(subject):

  do_something()

else:

  do_anotherthing()







12.创建一个正则表达式对象，然后通过该对象获得匹配细节





(Create an object with details about how the regex object matches (part of) a string)



reobj = re.compile(regex)

match = reobj.search(subject)

if match:

  # match start: match.start()

  # match end (exclusive): match.end()

  # matched text: match.group()

  do_something()

else:

  do_anotherthing()







13.用正则表达式对象获取匹配子串





(Use regex object to get the part of a string matched by the regex)



reobj = re.compile(regex)

match = reobj.search(subject)

if match:

  result = match.group()

else:

  result = ""







14.用正则表达式对象获取捕获组所匹配的子串





(Use regex object to get the part of a string matched by a capturing group)



reobj = re.compile(regex)

match = reobj.search(subject)

if match:

  result = match.group(1)

else:

  result = ""







15.用正则表达式对象获取有名组所匹配的子串





(Use regex object to get the part of a string matched by a named group)



reobj = re.compile(regex)

match = reobj.search(subject)

if match:

  result = match.group("groupname")

else:

  result = ""







16.用正则表达式对象获取所有匹配子串并放入数组





(Use regex object to get an array of all regex matches in a string)



reobj = re.compile(regex)

result = reobj.findall(subject)







17.通过正则表达式对象遍历所有匹配子串





(Use regex object to iterate over all matches in a string)



reobj = re.compile(regex)

for match in reobj.finditer(subject):

  # match start: match.start()

  # match end (exclusive): match.end()

  # matched text: match.group()







感兴趣的读者可以动手调试一下本文实例代码，相信会有新的收获。