Python3，字符串函数整理

rsplit从后往前分割

>>> "banana".split("n",1)
['ba', 'ana']
>>> "banana".rsplit("n",1)
['bana', 'a']
           

capitalize首字母大写

>>> 'GrEat'.capitalize()
'Great'
           

casefold：lower() 方法只对ASCII编码，也就是‘A-Z’有效，对于其他语言（非汉语或英文）中把大写转换为小写的情况只能用 casefold() 方法。

>>> 'GreaTEr'.casefold()
'greater'
           

非字母后的第一个字母将转换为大写字母

>>> "This is a 3g3g".title()
'This Is A 3G3G'
           

center，ljust，rjust

>>> "great".center(20, '*')
'*******great********'
>>> "great".ljust(20, '*')
'great***************'
>>> "great".rjust(20, '*')
'***************great'
           

count计数

"This is a dog".count("s")
2
           

expandtabs制表符转换为空格

>>> '\t'.expandtabs()
'        '
>>> '\t\t'.expandtabs()
'                '
           

partition、rpartition分割成三个元素并放入到元组中

>>> "This is a pig".partition("is")
('Th', 'is', ' is a pig')
>>> "This is a pig".rpartition("is")
('This ', 'is', ' a pig')
           

index，该方法与 python find()方法一样，只不过如果str不在 string中会报一个异常。

>>> 'This is a dog'.index("i", 4, 10)
5
           

swapcase大小写转换

>>> "GrEat".swapcase()
'gReAT'
           

translate，先做翻译表

>>> intab = "aeiou"
>>> outtab = "12345"
>>> trantab = str.maketrans(intab, outtab)   # 制作翻译表
>>> str = "this is string example....wow!!!"
>>> print (str.translate(trantab))
th3s 3s str3ng 2x1mpl2....w4w!!!
           

startswith。endswith

>>> "greater".startswith("great")
True
>>> "greater".endswith("er")
True
           

format_map，与format类似

>>> People = {"name": "john", "age": 33}
>>> print("My name is {name},iam{age} old".format_map(People))
My name is john,iam33 old