CODEWITHSUNDEEP
pythondictionary
Baltic Sun
Baltic Sun

Reputation: 185

removing items from an inventory(dictionary) if the value is zero

I am still very new to programming, and I ran into a problem here that I cannot seem to find a good answer for. Basically, I made a little program that lets you add and remove items from a dictionary. This is supposed to be like an inventory from an rpg game where you can open a chest and the contents will be added to the inventory, and when you you use items they will be removed from the inventory. I want to set it up where if there are zero or fewer of a particular item in the inventory, that item then disappears from the dictionary all together. This is where I am having some trouble. Here is my completed program

 inventory = {}

def add_to_inventory(item_tuple):
    inventory[item_tuple[0]]=item_tuple[1]


def add_all_items(tuple_list):
    for tup in tuple_list:
        if tup[0] not in inventory:
            add_to_inventory(tup)
        else:
            inventory[tup[0]]+=tup[1]
    return inventory 

def remove_items(item,quantity):
    global inventory
    updated_inventory={}
    for key,value in inventory.items():
        if key==item:
           value-=quantity
           inventory[key]=value
           if inventory[key]<= 0:
              inventory[key]=0
    for key,value in inventory.items():
        if value!=0:
            updated_inventory[key]= value
    inventory=updated_inventory

here is the program at work:

>>> chest=[("healing potion",3),("sword",1),("bread",5),("gold",50)]
>>> inventory
{}
>>> add_all_items(chest)
{'bread': 5, 'healing potion': 3, 'gold': 50, 'sword': 1}
>>> remove_items("bread",3)
>>> inventory
{'bread': 2, 'healing potion': 3, 'gold': 50, 'sword': 1}
>>> remove_items("bread",2)
>>> inventory
{'healing potion': 3, 'gold': 50, 'sword': 1}
>>>

I am pretty happy with how the first two functions look, but my remove_items function looks extremely sloppy, and I know there has to be a better way to do it even though it technically works. I tried using "pop" and "del", however I would get a Runtime error telling me that my dictionary changed size during iteration. So now I had to make a whole new inventory called updated_inventory and eventually after a roundabout process set it equal to "inventory" when it is correct. Like I said I have only been at this for a month, so I am assuming that there is something I could be doing better here, but so far this is the only way that works. I can tell from reading it that it looks poorly designed. Any recommendations on what I could to better? Thanks for the help.

Upvotes: 3

Views: 1212

Answers (1)

mattsap
mattsap

Reputation: 3806

I don't see why you need to search through the list of items. The point of a dictionary is to have immediate access.

You also don't need to duplicate the dictionary. Instead:

def remove_items(item,quantity):
    global inventory
    if item not in inventory: #make sure the item is in the inventory first
        return
    inventory[item] -= quantity
    if inventory[item] <= 0: #remove item if the quantity is less than 0
        inventory.pop(item,None)

Upvotes: 1

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