从 Python 中的列表中删除重复项

Question

I'm new to programming and I'm really stuck on trying to remove a certain amount of duplicates from a list.

I'm making a text based game and I'm trying to set up a shop where you can sell items.

If a player has, for example, 3 swords in his inventory and wants to sell 2 of them, keeping 1 of them in his inventory, I'm not sure how to implement this in to my code.

Example code:

option refers to the item they're selling eg 'sword'. valitems is a dictionary of various items in the game.

option4 = input('Enter selling quantity: ')
if option4 <= PlayerIG.inventory.count(option):
                    PlayerIG.inventory -= option4 * [option]
                    PlayerIG.gold += valitems[option]['SPrice']

I know this isn't working, however using "PlayerIG.inventory += option4 * [option]" got my buying side of the store system to work properly, but for some reason using the same code but for removing from the inventory, it does not seem to work.

Answer 1

You can do this by using the list.remove method. It deletes the first instance of the value you pass, so you will have to do this option4 number of times.

if option4 <= PlayerIG.inventory.count(
    # delete `option` from inventory `option4` number of times
    [PlayerIG.inventory.remove(option) for i in range(option4)]
    gold += valitems[option]['SPrice']

You could use a defaultdict from the collections module to manage your inventory.

from collections import defaultdict

# create a default dict with 0 as the default value
inventory = defaultdict(int)

You can add or remove items to/from the inventory as follows:

# add
inventory[item] += number_of_items

# remove
number_of_items = input('Enter selling quantity: ')
item = input('Enter item to sell: ')

if number_of_items <= inventory[item]:
    inventory[item] -= number_of_items

Bear in mind that option and item need to be hashable for this to work. If they are strings, they are hashable.