此代码缺少什么？我试图使用.count（）函数来获得总计，但我一直在获得0s

Question

我正在使用.csv文件导入列表。现在已经编译了列表，我需要获得总计，并且我决定使用.count函数。列表名称是参与者[]。参与者列表中的每个条目都有100个条目： 与会者[姓名，状态，菜单_selection，fee_paid]

当我输入此代码时，我的总数等于0。我在编码方面非常新，并假设我缺少列出列表的东西。是否有人建议我如何将其适当地总计这些物品？这是所讨论的代码的一部分：

## Get Totals for each item in the attendee list.
def get_totals(attendees): 
        member = attendees.count('Member') #count of occurrences of members in attendees list
        print("~~~~~~~~~~~~~~~~~~~~~~~~")
        print(f"Total Members attending:        {member}")## display totals
        guest = attendees.count('Guest')   #count of occurrences of guests in attendees list
        print(f"Total Guests attending:         {guest}")## display totals
        child = attendees.count('Child')   #count of occurrences of children in attendees list
        print(f"Total Children attending:       {child}")## display totals
        print("======================================")
        fee_paid = 21
        total_attendees = member + guest + child
        print(f"Total Attendees:                {total_attendees}") ## display totals
        total_fees = total_attendees * fee_paid
        print(f"Total fees collected:           {total_fees}") ## display totals
        print("~~~~~~~~~~~~~~~~~~~~~~~~")
        chicken = attendees.count("Chicken")#count of occurrences of chicken in attendees list
        print(f"Total Chicken entrees:          {chicken}")## display totals
        beef = attendees.count("Beef")      #count of occurrences of beef in attendees list
        print(f"Total Beef entrees:             {beef}")## display totals
        veg = attendees.count("Vegetarian") #count of occurrences of vegetarian in attendees list
        print(f"Total Vegetarian entrees:       {veg}")## display totals
        print("~~~~~~~~~~~~~~~~~~~~~~~~")
        print()
        break

这是我在执行代码时看到的：

Command: total
~~~~~~~~~~~~~~~~~~~~~~~~
Total Members attending:        0
Total Guests attending:         0
Total Children attending:       0
======================================
Total Attendees:                0
Total fees collected:           0
~~~~~~~~~~~~~~~~~~~~~~~~
Total Chicken entrees:          0
Total Beef entrees:             0
Total Vegetarian entrees:       0
~~~~~~~~~~~~~~~~~~~~~~~~

有人可以提供帮助吗？

Answer 1

因此，首先澄清与会者项目，因此我们同意：这是每个项目尚存的项目列表另一个列表，其中包含name ，<代码>状态，菜单> Selection和fee_paid。

如果是这种情况，则与会者中的每个项目列表是列表SO none 它们将等于字符串“成员” （例如）。这就是为什么您的计数始终为零。

最好的选择是构建您 感兴趣的东西的列表并进行检查。对于的状态“成员”和菜单选择“ beef”，它会像以下内容一样：

def get_totals(attendees):
    # Get individual lists

    statuses = [item[1] for item in attendees]
    selections = [item[3] for item in attendees]

    member = statuses.count("Member")
    chicken = selections.count("Chicken")

---

说，我必须承认我是使用的忠实拥护者量身定制的数据结构（以及针对非平凡代码的键入提示），而不是库存列表和词典。这样做可以使这些工具可以拿走许多python疼痛点可以正确地完成工作（例如Pylint和mypy）。

换句话说，类似的东西：

import dataclasses as dc
import typing as typ

@dc.dataclass
class Attendee:
    """ Specific data type for a single attendee, along
        with counting match functions as needed.
    """
    name: str
    status: str
    menu_selection: str
    fee_paid: float

    def status_match(self, check_list: typ.List[str]) -> int:
        """ Allows summation of attendees matching status.
        """
        return 1 if self.status in check_list else 0

    def menu_match(self, check_list: typ.List[str]) -> int:
        """ Allows summation of attendees matching menu selection.
        """
        return 1 if self.menu_selection in check_list else 0

@dc.dataclass
上课参加：
“”“参与者的列表类型，包括计数方法
在整个集合中。
”“”
与会者：typ.list [参与者]

def __init__(self):
    self.attendees = []

def add(self, item: Attendee) -> None
    self.attendees.append(item)

def count_status(self, statuses: typ_List[str]) -> int:
    return sum([item.status_match(statuses)
        for item in self.attendees])

def count_selection(self, selections: typ_List[str]) -> int:
    return sum([item.selection_match(selections)
        for item in self.attendees])

# And any other things such as deleting or enumerating.

---

然后，您将列表构建列表（取决于您如何阅读CSV数据）：

attendees = AttendeeCollection()
for entry in get_csv_lines:
    attendees.add(Attendee(name=entry[0], status=entry[1],
        menu_selection=entry[2], fee_paid=entry[3]))

---

您要计算的代码，然后看起来更像是出于目的而编写的，而不是仅使用非常低- 级别的数据结构：

member = attendee_list.count_status(["Member"])
guest =  attendee_list.count_status(["Guest"])

chicken = attendee_list.count_selection(["Chicken"])
chicken_or_beef = attendee_list.count_selection((["Chicken", "Beef"])

现在，我并不建议您更改您的代码，只是现代Python提供的（但不是授权，这是一件好事）的方法来开发具有所有内容的软件C ++等静态定义的语言的优点。