python学习-54 正则表达式2

re模块 之分组

>>> import re
>>> re.findall("ab|c","sdfab|csdf")
['ab', 'c']
>>> re.findall("ab|cd","sdfab|cdsdf")
['ab', 'cd']
>>> re.findall ("abc+","abccccc")
['abccccc']
>>> re.findall ("abc*","abccccc")
['abccccc']
>>> re.findall("(abc)+","abcabcabcabc")               # 分组
['abc']
>>> re.findall ("(abc)*","abcabcabcabc")
['abc', '']
>>> re.findall ("abc+","abcabcabcabcabc")
['abc', 'abc', 'abc', 'abc', 'abc']

search分组用法 （只返回一个对象）

>>> re.search("(?P<name>\w+)","abcccc")
<re.Match object; span=(0, 6), match='abcccc'>
>>> re.search("(?P<name>\w+)","abcccc").group()
'abcccc'

根据组名称 提取内容

>>> re.search("(?P<name>[a-z]+)\d+","john18musicxiaoming20movie").group("name")
'john'
>>> re.search("(?P<name>[a-z]+)(?P<age>\d+)","john18musicxiaoming20movie").group("age")
''
>>> 

re模块的其他常用方法

>>> re.match("\d+","44safs45asdf321saf789").group()       # 只取一个对象，只能取开头的
''
>>> re.split(" ","hello world")                         # 按空格为分界线取
['hello', 'world']
>>> re.split("[ |]","hello world|aaa")
['hello', 'world', 'aaa']
>>> re.split("[ab]","safdbds")                         # 按 a  b 为分界线取
['s', 'fd', 'ds']

--替换

>>> re.sub("\d+","A","a1sd4fg45h")
'aAsdAfgAh'
>>> re.sub("\d","A","a1sd4fg45h")
'aAsdAfgAAh'
>>> re.sub("\d+","A","a1sd4fg45h",2)
'aAsdAfg45h'

>>> a = re.compile ("\d+")         # 定义规则
>>> a.findall("safsd12a45")           # 直接调用 （可以调用多次）
['', '']

>>> re.finditer ("\d+","asfa45saf56")         # 将数字放到迭代器内存里
<callable_iterator object at 0x00000220B1E50E80>

获取里面的内容

>>> b = re.finditer ("\d+","asfa45saf56")
>>> next(b)
<re.Match object; span=(4, 6), match=''>
>>> next(b)
<re.Match object; span=(9, 11), match=''>

优先级

>>> re.findall("www\.(baidu|123)\.com","www.baidu.com")
['baidu']
>>> re.findall("www\.(?:baidu|123)\.com","www.baidu.com")     # ‘ ？：’去掉优先级
['www.baidu.com']