Question

我正在用Python编写自动售货机模拟作为学校作业，我需要编辑一个特定的行以保持库存清单的最新状态。

以下是代码：

import csv

with open('stock.csv','r') as STOCK_READ: #Counts the amount of items in the CSV file
    ITEM_COUNT = 0
    reader = csv.reader(STOCK_READ)
    for line in reader:
        ITEM_COUNT = ITEM_COUNT + 1

def GET_STOCK_COUNT():
    with open('stock.csv', 'r') as STOCK_READ:
        reader = csv.reader(STOCK_READ)
        for line in reader:
            print("{0} - {1} - {2} in stock".format(line[0],line[1],line[2]))

while True:
    GET_STOCK_COUNT()
    CHOSEN_ITEM = int(input("Input number of desired item: "))

这是CSV（它是：项目编号，名称，股票）：

1,Coca Cola,10
2,Monster,10
3,Monster Ultra,10

通过让用户选择号码，我想让CSV编写器转到正确的行并在最后更改数字。

Answer 1

这是使用字典的好地方。如果在GET_STOCK_COUNT函数中将数据保存到字典中，然后返回字典，则可以访问该字典，然后根据需要修改数据。

def GET_STOCK_COUNT():
    stock = {}
    with open('stock.csv', 'r') as STOCK_READ:
        reader = csv.reader(STOCK_READ)
        for line in reader:
            stock[line[0]] = {
                'name': line[1],
                'stock': line[2],
            }

    return stock

这将允许您通过股票指数编号引用项目。例如，如果您想更改订单项的库存，则可以执行以下操作：

stock = GET_STOCK_COUNT()
stock[CHOSEN_ITEM]['stock'] = new_value

您需要编写一个新功能来打印您的库存清单，但现在您可以访问这些数据，这样仍然可以。

Answer 2

你走的很好。您需要一个函数来更新您的文件，就像您阅读它一样。我已经写了这样一个函数。你走了：

import csv

with open('stock.csv','r') as STOCK_READ: #Counts the amount of items in the CSV file
    ITEM_COUNT = 0
    reader = csv.reader(STOCK_READ)
    for line in reader:
        ITEM_COUNT = ITEM_COUNT + 1

def GET_STOCK_COUNT():
    with open('stock.csv', 'r') as STOCK_READ:
        reader = csv.reader(STOCK_READ)
        for line in reader:
            print("{0} - {1} - {2} in stock".format(line[0],line[1],line[2]))

def UPDATE_STOCK_COUNT(item_id):
    with open('stock.csv', 'r') as STOCK_READ:
        reader = csv.reader(STOCK_READ)
        output = []
        for line in reader:
            if line[0] == item_id:
                line[2] = str(int(line[2])-1)
            output.append(line)
    with open('stock.csv', 'w', newline='') as STOCK_WRITE:
        writer = csv.writer(STOCK_WRITE)
        writer.writerows(output)

while True:
    GET_STOCK_COUNT()
    CHOSEN_ITEM = input("Input number of desired item: ")
    UPDATE_STOCK_COUNT(CHOSEN_ITEM)

在Python CSV中修改特定单元格

2 个答案: