Question

我正在尝试创建一个购物清单，在您按1时向您显示包含购物清单的文件，当您按2时添加一个新商品，按3时删除一个商品，并在按4时退出。我不知道该为＃3做些什么。

老实说，我什至不知道如何开始。

    elif (number == 3):
        delete_item = input('What item would you like to delete?')

应该从文件中删除用户不需要的内容。

Answer 1

这是一个示例，如果您想使用JSON格式将购物清单存储在文件中。我提供了一个用于编写，阅读和删除/覆盖的示例。

import json

shopping_list = ["bread", "apple", "carrot"]

# Writing
with open('shopping.txt', 'w') as fh:  
    json.dump(shopping_list, fh)

# Reading
with open('shopping.txt', 'r') as fh:
    shopping_list = json.load(fh)

# Deleting and rewriting
try:
    # Here we remove an entry "apple" from the shopping list
    shopping_list.remove("apple")
except ValueError:
    # In the case that the entry does not exist, do not error
    pass

with open('shopping.txt', 'w') as fh:  
    json.dump(shopping_list, fh)

Answer 2

以下程序应该可以完成您想要的工作。

由于未指定搜索方法，选项3扫描整个数组并删除由value指定的项目。

import os

shopping_list = ['foo', 'foo1', 'foo2']

def main():
    action = input("Please select an action: 1-4: ")

    if action == "1":
        print(os.path.dirname(os.path.realpath(__file__)))
    elif action == "2":
        item_to_add = input("Please type what you want to add: ")
        shopping_list.append(item_to_add)
        print(shopping_list)
    elif action == "3":
        item_to_delete = input("Please type exactly what you want to delete: ")
        for curr in shopping_list:
            if curr == item_to_delete:
                shopping_list.remove(curr)
        print(shopping_list)
    elif action == "4":
        print ("Exiting")
        exit
    else:
        print("You did not enter 1-4")

main()

Answer 3

如果x是要从列表中删除的元素的名称，而shopping_list是列表，则可以这样使用列表理解：

shopping_list = [y for y in shopping_list if y!=x]

从python中的购物清单文件中删除商品

3 个答案: