python - 类型错误 : __new__() missing 2 required positional arguments: 'shares' and 'price'

Question

我正在尝试使用namedtuple

from collections import namedtuple
Stock = namedtuple('Stock', ['name', 'shares', 'price'])

def compute_cost(records):
    total = 0.0
    for rec in records:
        s = Stock(*rec)
        total += s.shares * s.price
    return total

with open('r.txt') as f:
    content = f.readlines()
    content = [x.strip() for x in content]   
    for i in content:
         p = compute_cost(i)
    print (p)

看来我有问题，我如何使用位置参数。

  File "b74.py", line 15, in <module>
    p = compute_cost(i)
  File "b74.py", line 7, in compute_cost
    s = Stock(*rec)
TypeError: __new__() missing 2 required positional arguments: 'shares' and 'price'

这是我的文本文件

hmf Kiza 100 2.33
piz Miki 999 0.75
air Dush 500 8.50

Answer 1

此错误消息意味着您没有向 Stock() 构造函数传递足够的参数。您的元组有 3 个元素，因此您需要将 3 个参数传递给构造函数。

但是在这一行中:

for rec in records:

records 是文件中的一行。因此 rec 只是单个字符。

提示:for record.split("")