CODEWITHSUNDEEP
pythonfor-loop
user3896917
user3896917

Reputation:

ValueError with for loop with two iterators Python

I am experimenting with replacing a block of if/ elif statements which are all very similar with a for loop that changes the conditions of one for loop a few times.

My original if/ elif statements are for an item system of an RPG I am coding. Each type of item can only go in certain slots of the inventory.

def PickUpItem(self): #Adds an item to the inventory in a space depending on its type

if self.Type == 1 and not Inventory[0]: #Type 1 is a weapon type, 2 is for shields, etc.
        Inventory[0] = self #Sets the weapon inventory slot to the object

    elif self.Type == 2 and not Inventory[1]:
        Inventory[1] = self

    elif self.Type == 3 and not Inventory[2]:
        Inventory[2] = self

So, here is the code I am trying to replace the previous with so that it will check each of the if/ elif statements' pairs of conditions:

def PickUpItem(self):
   for i, j in range(1, 4), range(3):
        if self.Type == i and not Inventory[j]:
            Inventory[j] = self

I think this should work, but I get the error:

    for i, j in range(1, 4), range(0, 3):
ValueError: too many values to unpack (expected 2)

Upvotes: 0

Views: 60

Answers (2)

jh314
jh314

Reputation: 27802

You can set j = i - 1 in your loop:

for i in range(1,4):
    j = i - 1
    if self.Type == i and not Inventory[j]:
        Inventory[j] = self

Upvotes: 0

David Robinson
David Robinson

Reputation: 78590

What you're looking for is zip:

for i, j in zip(range(1, 4), range(0, 3)):

The reason (as you could confirm in an interactive terminal) is that zip(range(1, 4), range(0, 3)) has the value [(1, 0), (2, 1), (3, 2)].

However, note that your code could be much more easily written as

if not Inventory[self.Type - 1]:
    Inventory[self.Type - 1] = self

Upvotes: 1

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