Python count total items in dictionary

Question

So I want to count up all the values together to make a totalItems var which will be printed underneath the list. the output gives me 5 instead of it all being counter up. Can someone explain me why, not just give the right code.

stuff = {'coins': 5, 'arrows': 42, 'rope': 1}


def getInvent(inventory):

    itemTotal = 0
    print('Inventory:')
    print(str(stuff['coins']) + '  Coins')
    print(str(stuff['arrows']) + ' Arrows')
    print(str(stuff['rope']) + '  Rope')   

    for k, v in stuff.items():
        itemTotal = itemTotal + v
        print('Total number of items: ' + str(itemTotal)) 
        return itemTotal

getInvent(stuff)

There is indentation problem with your code. `return itemTotal` is inside the for loop and hence after the first iteration `5` is returned and rest are not counted. A simpler code would be - `sum(stuff.values())`. — Gurupad Mamadapur, Mar 25 '17 at 19:36

Julien · Answer 1 · 2017-03-25T19:43:33.477

3

You can turn the for loop into a one-liner with sum() and dict.values():

>>> sum(stuff.values())
48

Explanation:

stuff.values() gives you a list of all the values in the dictionary:

>>> stuff.values()
[1, 5, 42]

sum() adds together all items in an iterable (like a list):

>>> sum([1, 5, 42])
48

Full example:

stuff = {'coins': 5, 'arrows': 42, 'rope': 1}

def getInvent(inventory):
    print('Inventory:')
    print(str(stuff['coins']) + '  Coins')
    print(str(stuff['arrows']) + ' Arrows')
    print(str(stuff['rope']) + '  Rope')   

    itemTotal = sum(inventory.values())
    print('Total number of items: ' + str(itemTotal)) 
    return itemTotal

getInvent(stuff)

edited Mar 25 '17 at 19:43

answered Mar 25 '17 at 19:34

Julien

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Julien just beat me to this, sum the list of values is the easiest way to do this in a single readable line of code – Mr-F Mar 25 '17 at 19:38
Thank you, and I saw something about sum() on stackoverflow, but the thing is, I'm following rules of a book. The rules were not to use sum() since I have not been able to learn that yet. – Mees Mar 26 '17 at 17:06

score 1 · Answer 2 · answered Mar 25 '17 at 19:31

You should not return inside your loop because in that case it returns immediately (in the first iteration of the loop). Instead, put the return outside the loop.

for k, v in stuff.items():
    itemTotal = itemTotal + v
    print('Total number of items: ' + str(itemTotal)) 
return itemTotal

A function will return immediately when it encounters the return statement. So you should ensure that your loop runs in its entirety before returning the value.

I didn't even notice it! Thank you so much. This is exactly what I searched for! — Mees, Mar 26 '17 at 17:10

Python count total items in dictionary

2 Answers2