Using two lists in a loop to assign two arguments in one function

Question

I have a function with 2 arguments. I would like to display the output using varying inputs of the arguments that can be found in two lists using a loop. I have executed the code successfully with one list (ages) but not with (ages) and (game).

# the below code works for 1 list assignment to the a argument  

for a in ages:
    print(age_price_event(a, 2))

# when I try this to assign the other argument I get an error.

for a in ages b in game:
    print(age_price_event(a, b))

File "", line 1 for a in ages b in game: ^ SyntaxError: invalid syntax

# Here is the function that I wrote

# Function that has two elements 
# a is the age of person
# b is the game
def age_price_event(a, b):
    str(b)
    if b == 1:            # looks to see if it is for 1
        if a < 4:              # if so execute code below
            return (0)    
        elif a < 18:
            return (10)
        else:
            return(15)     #Stop here
    if b==2:                     # looks to see if it is for 2
        if a < 4:                     # if so execute code below
            return (5)
        elif a < 18:
            return (55)
        else:
            return(66)                  #Stop Here
    else:               # if not game is not toady
        return ("That Game is not Today")

# here are the list to be assign to the arguments 
ages = [11, 22, 14, 25]
game = [ 1, 1, 2, 3]

# the below code works for 1 list assignment to the a argument  

for a in ages:
    print(age_price_event(a, 2))

# when I try this to assign the other argument I get an error.

for a in ages b in game:
    print(age_price_event(a, b))

the below code works for 1 list assignment to the a argument

when I try this to assign the other argument I get an error.

File "<ipython-input-158-2d5fb2f7d37f>", line 1
    for a in ages b in game:
                  ^
SyntaxError: invalid syntax

Use two for loops: `for a in ages:` `for b in games:` `print(age_price_event(a,b))` — sacuL, Jul 20 '19 at 15:39
What is this `for a in ages b in game:` supposed to do? You want two `for` loops or a `zip` depending on what you want to pass to the function. — Austin, Jul 20 '19 at 15:41
In your function, why do you convert b to string and then check `if b == 1`? — FObersteiner, Jul 20 '19 at 15:42
Good point, I was originally using it as a string input but changed to numerical. — in0, Jul 20 '19 at 15:47
@MrFuppes, `b` still is *not* a string unless it is assigned back. — Austin, Jul 20 '19 at 15:51
Possible duplicate of [How to iterate through two lists in parallel?](https://stackoverflow.com/questions/1663807/how-to-iterate-through-two-lists-in-parallel) — Georgy, Jul 20 '19 at 15:59

score 1 · Answer 1 · answered Jul 20 '19 at 15:41

1

This is called parallel iteration and can be written as follows:

for a, b in zip(ages, games):

answered Jul 20 '19 at 15:41

NPE

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score 0 · Answer 2 · answered Jul 20 '19 at 16:05

Python 3

for a, b in zip(ages, game):
    print(age_price_event(a, b))

Python 2

import itertools

for a, b in itertools.izip(ages, game):
    print(age_price_event(a, b))

In python 2 itertools.izip returns iterator instead of list, you want to use in Python 2 itertools.izip if you have so many elements.

Using two lists in a loop to assign two arguments in one function

2 Answers2