Python iterating through pair of values in list for function

Question

I have a list like

cases = [(1,1), (2,2), (3,3)]

trying to write a function that calculates through each item and return values:

def case_cal(cases)
    for x, y in cases:
        result = x+y
        return result

output = case_cal(cases)
print(output)

I like to get output like

2
4
6

But I only get

2

I am a newbie learning python and something simple I am missing here. Could I get any advice? Thanks in advance!

Answer 1

Once you return something you move out of the function. So make a list, append your values to the list and then return in the end.

def case_cal(cases):
    ret_values = []
    for x, y in cases:
        result = x+y
        ret_values.append(result)
    return ret_values

output = case_cal(cases)
print(*output)

Answer 2

Your code returns inside the for loop, at the end of the first iteration, so you'll only see the first x + y result.

This is a perfect use for a generator, which will allow you to grab the next x + y calculation on demand and offer maximum control over what the caller can do with the result:

cases = [(1,1), (2,2), (3,3)]

def case_cal(cases):
    for x, y in cases:
        yield x + y

for x in case_cal(cases):
    print(x)

Output:

2
4
6