映射名称到序列元素

1. collections.namedtuple()函数可以定义字段的传递值

from collections import namedtuple
subs = namedtuple('subss',['addr','join'])
sub = subs('jonesy@example.com', '2012-10-19')
print(sub) #subss(addr='jonesy@example.com', join='2012-10-19')

- 可以解压索引

addr,join = sub
print(addr,join) #'jonesy@example.com' '2012-10-19'

2. 如果不使用以上方法，也可以使用普通元组代码

-  但是看起来很难理解

from collections import namedtuple
stock = namedtuple('stock',['name','shares','prices'])
def cost1(records):
    for rec in records:
        total = 0.0   
        s = stock(*rec)
        total += s.shares * s.prices
    return total
prinr(stock('acme',100,123.5)) #stock(name='acme', shares=100, prices=123.5)