Cannot divide two dictionaries in Python

Question

I'm trying to divide a dictionary by another dictionary and I cannot find a solution online that works.

Code:

def getRatio(price_a, price_b):
    """ Get ratio of price_a and price_b """
    """ ------------- Update this function ------------- """
    """ Also create some unit tests for this function in client_test.py """
    if (price_b == 0):
        # avoid zero division error
        return

    return price_a / price_b

Output:

line 51, in getRatio
    return price_a / price_b
TypeError: unsupported operand type(s) for /: 'dict' and 'dict'

Answer 1

The following code returns the ratios as a dictionary with A's keys. If this is not the desired behavior, please clarify.

The solution using dictionary comprehension:

a = {'A':1, 'B':5, 'D':6}
b = {'X':4, 'Y':8, 'Z':4}

{key:val_a/val_b for ((key, val_a), val_b) in zip(a.items(), b.values())}

# Output:
# {'A': 0.25, 'B': 0.625, 'D': 1.5}

If you want the ratios as an array without the keys, you can use list comprehension:

[val_a/val_b for (val_a, val_b) in zip(a.values(), b.values())]
# Output for example above
# [0.25, 0.625, 1.5]