python 字符串(string) format介绍和代码
你可以用字符串的format方法来格式化输出字符串。 比如；
>>> print 'We are the {0} who say "{1}!"'.format('knights', 'Ni')
We are the knights who say "Ni!"
We are the knights who say "Ni!"
括号内的字符（称为格式字段）被替换的对象。{}括号中的数字是指替换的位置，里面的数字，比如0,1表示替换元组的索引位置。
>>> print '{0} and {1}'.format('spam', 'eggs')
spam and eggs
>>> print '{1} and {0}'.format('spam', 'eggs')
eggs and spam
spam and eggs
>>> print '{1} and {0}'.format('spam', 'eggs')
eggs and spam
如果使用关键字参数的格式方法，其值被称为使用的参数名称。
>>> print 'This {food} is {adjective}.'.format(
... food='spam', adjective='absolutely horrible')
This spam is absolutely horrible.
... food='spam', adjective='absolutely horrible')
This spam is absolutely horrible.
下面是位置和关键字参数的任意组合：
>>> print 'The story of {0}, {1}, and {other}.'.format('Bill', 'Manfred',
... other='Georg')
The story of Bill, Manfred, and Georg.
... other='Georg')
The story of Bill, Manfred, and Georg.
