python - 如何统计文本文件中重复单词的数量？

Question

自动售货机程序的代码示例

item = int(input("What item do you want: [1-10]"))
item_chosen = open("items.txt","a")
item_chosen.write(str(item))
item_chosen_data = items_chosen.read()    
item_chosen.close()

从这里，我如何能够检查文本文件中存储了每个商品编号的数量(因为自动售货机在商品“不可用”之前应该只有有限的库存)？

Answer 1

item = int(input("What item do you want: [1-10]"))

# use the with open structure to work with files without having to explicitly close them
with open("items.txt","a+") as item_chosen:
    item_chosen.write(str(item))
    item_chosen_data = item_chosen.read()

# Use the string.split() method to get the item_chosen_data as a list instead of a string.
item_chosen_data = item_chosen_data.split()

# Create a set from the list of items, the removes duplicate values.
unique_items = set(item_chosen_data)

# Initialize a dictionary to map each item to it's count.
item_to_count = {}

# for each unique item
for item in unique_items:
    # map the item to the number of times it appears in the list (ie. list.count() method)
    item_to_count[item] = item_chosen_data.count(item)

我希望我所做的评论是不言自明的，但如果需要更多信息，请告诉我。本质上，您希望将从文本文件中读取的信息分解为列表，这允许您使用 list.count() 方法。

此外，就像其他人提到的那样，在此任务中完全避免写入文件可能是有益的。另一种方法是定义一个字典，其中包含自动售货机中每个商品的编号，例如:

# build a dictionary mapping each item to it's stock
item_to_stock = {'coke': 3, 'pepsi': 2, 'apple_juice': 5, 'doritos': 3}

# put a coke into the vending machine:
item_to_stock['coke'] = item_to_stock.get('coke', 0) + 1

# take a pepsi out of the vending machine, first check if the item is in stock
if item_to_stock.get('pepsi') > 0:
    item_to_stock['pepsi'] = item_to_stock['pepsi'] - 1