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Python Functional Python The Lambda Lambada Reduce

Posted by Mark Chesney
Mark Chesney
11,747 Points

product_sales; reduce()

Bummer: product_sales threw an exception when given the argument (10.5, 2)

Treehouse, let's talk about this exception. It doesn't happen on my console

>>> product_sales(10.5, 2)
21.0
>>>
prices.py 
prices = [
    (6.99, 5),
    (2.94, 15),
    (156.99, 2),
    (99.99, 4),
    (1.82, 102)
]

def product_sales(price, units):
    return price * units

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,457 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points

Your are close. In the directions it says "function named product_sales that takes a single two-member tuple". So instead, you may have:

def product_sales(tuple_value):
    price, units = tuple_value
    # ...
Mark Chesney
Mark Chesney
11,747 Points

Thanks Chris...

hmm... now this works to pass step 1 of the challenge, but it throws an error in my console:

def product_sales(tuple_value):
    price, units = tuple_value
    return price * units

TypeError: product_sales() takes 1 positional argument but 2 were given

However, if I add the asterisk to make it *tuple_value, then this fails the challenge but works on my console.

Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,457 Points

Now that product_sales is expecting a tuple, it needs to be called with a tuple, such as:

product_sales((6.99, 5))
Mark Chesney
Mark Chesney
11,747 Points

Ah yes, thank you Chris!