python - 关于简单python脚本的问题

Question

我有一个家庭作业，要写一个简单的购物 list ，脚本应该能够:

1. 接受用户输入的变量，例如商品的商品名称、数量和成本

2. 使用从用户那里收集的信息，创建一个字典条目并将其添加到名为 grocery_history 的列表中

3. 按照以下格式打印出所有输入的项目:变量→数字名称价格item_total

4. 最后输出所有项目的成本总和

这是我的代码:

grocery_item = {}
grocery_history=[{}]
stop = 'go'
item_name = input("Item name:")
quantity = input("Quantity purchased:")
cost = input("Price per item:") 
grocery_history.append(item_name)
grocery_history.append(quantity)
grocery_history.append(cost)

cont = input("Would you like to enter another item?\nType 'c' for continue or 'q' to quit:")
while cont != 'q':
  item_name = input("Item name:")
  quantity = input("Quantity purchased:")
  cost = input("Price per item:") 
  cont = input("Would you like to enter another item?\nType 'c' for continue or 'q' to quit:")


  grocery_history.append(item_name)
  grocery_history.append(quantity)
  grocery_history.append(cost)



grand_total = []

number = grocery_history[quantity]
price = grocery_history[cost]

for grocery_history in grocery_item:    
  item_total = int(number)*float(price)
  grand_total.append(item_total)
   print(grocery_history[number][name] + "@" [price]:.2f + "ea'.format(**grocery_item)")     


item_total = 0


print ("Grand total:" + str(grand_total))

在我的 number = grocery_history[quantity] price = grocery_history[cost]statement I get aKey Error 2`，我不确定为什么，这些键应该存在，但也许它们没有正确添加到列表中。任何帮助将不胜感激，如果您需要更多详细信息，请告诉我，我将对其进行编辑。

Answer 1

这是一个工作示例(解释如下):

grocery_history={'item_name':[], 'quantity':[], 'cost':[]}
cont = 'c'
while cont != 'q':
    item_name = input("Item name:")
    quantity = int(input("Quantity purchased:"))
    cost = int(input("Price per item:"))
    cont = input("Would you like to enter another item?\nType 'c' for continue or 'q' to quit:")

    grocery_history['item_name'].append(item_name)
    grocery_history['quantity'].append(quantity)
    grocery_history['cost'].append(cost)


grand_total = 0
for i in range(len(grocery_history['item_name'])):
    item_name = grocery_history['item_name'][i]
    quantity = grocery_history['quantity'][i]
    cost = grocery_history['cost'][i]

    priceTimesQuantity = quantity * cost
    grand_total = grand_total + priceTimesQuantity
    message = 'Bought {} x{} (each: {}$) to a total of: {}'.format(item_name, quantity, cost, priceTimesQuantity)
    print( message )

finalmessage = 'Grand Total: {}'.format(grand_total)
print(finalmessage)

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1. 我减少了你第一个循环上面的部分(考虑一下)
2. grocery_history 现在是一个包含 3 个列表的字典。示例:
   
3. 我们现在用项目向下填充这些列表(append)
4. 当用户完成后，我们再次遍历以 i 为索引的列表
   (请参阅图像左侧的小灰色数字)然后，对于每个项目，我们从列表中加载详细信息并计算总价格此外，我们将总数添加到 grand_total，这是一个数字(从零开始)与第二个循环相加。
5. 在第二个循环完成后，我们打印最终值(总和)

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在 Texts 中:"some text {}".format(var) - {} 是 var 之后的占位符字符串