Python function 里面有打开的文件：只有第一个列表理解“调用”工作正常？

Question

我有一个包含多个重复值的 csv 文件。 用 csv.DictReader 安装了一个包含大量字典的巨大列表，列表的每个值是这样分隔的：(fieldnames=['person', 'food', 'weekday'])。

我不认为 csv 文件内容对问题很重要，所以我没有复制它。

大多数问题，我只需要找到一个过滤值，所以我使用了一个带有理解的计数器和/或列表。

现在我需要找出所有可能的“食物”和一个特定“人”消耗的“食物”之间的区别。

所以我需要将两个列表与列表理解进行比较。

我的代码：

import csv
from typing import Counter

def analyze_log(path_to_file):
    with open(path_to_file) as f:
        csv_opened_file = csv.DictReader(
            f, fieldnames=['name', 'food', 'weekday'])


        def person_favorite_meal(opened_file, person):
            person_orders = Counter(
                order['food'] for order in opened_file if order['name'] == person
            )  # this works
            return max(person_orders, key=person_orders.get)


        def person_how_many_ordered(opened_file, person, meal):
            person_orders = Counter(
                order['food'] for order in opened_file if order['name'] == person and order['food'] == meal
            )  # this works
            return person_orders[meal]


        def person_never_ordered(opened_file, person):
            every_ordered_meal = Counter([order['food'] for order in opened_file])  # this works
            person_ordered_meals = Counter([
                order['food'] for order in opened_file if order['name'] == person
            ])  # this DOESN'T work
            
            list_difference = [
                meal for meal in every_ordered_meal if meal not in person_ordered_meals]

            return f"1- {person_ordered_meals} 2- {every_ordered_meal}"


print(person_never_ordered(csv_opened_file, 'maria'))
analyze_log('../data/orders_1.csv') # the file is read

问题：只有 function 'person_never_ordered' 中的第一个列表可以正常工作。

就像我有这样的代码：

 def person_never_ordered(opened_file, person):
            every_ordered_meal = Counter([order['food'] for order in opened_file])  # this comes first, it works
            person_ordered_meals = Counter([
                order['food'] for order in opened_file if order['name'] == person
            ])  # this DOESN'T work
            
            list_difference = [
                meal for meal in every_ordered_meal if meal not in person_ordered_meals]

            return f"1- {person_ordered_meals} 2- {every_ordered_meal}"


print(person_never_ordered(csv_opened_file, 'maria'))
analyze_log('../data/orders_1.csv') # the file is read

我得到这样的控制台：

1- Counter() 2- Counter({'hamburguer': 33, 'pizza': 8, 'coxinha': 8, 'misto-quente': 7})

但如果我只是切换列表顺序，代码如下：

def person_never_ordered(opened_file, person):
                person_ordered_meals = Counter([
                    order['food'] for order in opened_file if order['name'] == person
                ])  # now this comes first, and it works
    
                every_ordered_meal = Counter([order['food'] for order in opened_file])  # now this comes second first, and it doesn't work!

                
                list_difference = [
                    meal for meal in every_ordered_meal if meal not in person_ordered_meals]
    
                return f"1- {person_ordered_meals} 2- {every_ordered_meal}"
    
    
    print(person_never_ordered(csv_opened_file, 'maria'))
    analyze_log('../data/orders_1.csv') # the file is read

我得到了这个控制台：

1-计数器（{'汉堡包'：16，'披萨'：8，'coxinha'：8}）2-计数器（）

为什么会这样？

Answer 1

您不能调用在另一个 function 中定义的 function ，这样您必须全局定义您的函数才能在您的代码的 Z65E8800B5C6800AAD896F888B2A62A 中使用它们

使固定：

• 将定义移到分析之外 function
• 或尝试在每个定义之前添加全局