Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python Functional Python The Lambda Lambada Reduce

What is the correct use of map, add, reduce and product

Python IDE returns the in my opinion correct result of the requested challenge step which is a total of 978.63, right? Answer: Didn't find the correct use of reduce, map, add and product_sales. Why?

from operator import add
from functools import reduce

prices = [
    (6.99, 5),
    (2.94, 15),
    (156.99, 2),
    (99.99, 4),
    (1.82, 102)

def product_sales(items):
    return items[0] * items[1]

total = reduce(add, (map(product_sales, prices)))

3 Answers

Okay found it. I used unneccessary paranthesis around the map statement for the add function.

Parsenz Dev
Parsenz Dev
13,198 Points

Take out the extra parentheses you've got around the map function. The last line should read:

total = reduce(add, map(product_sales, prices))