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pythonlistreducepython-itertools

Multiplying paired elements in python using reduce

For a list like: 

a = [1,2,3,4,5,6]

I want to use the code below to multiply paired elements like this: 

(a[0] + a[1]) * (a[2] + a[3]) * (a[4] + a[5])

I've tried using something like:

reduce((lambda x, y: (x+y)), numbers)

and:

reduce((lambda x, y: (x+y)*(x+y)), numbers)

But I don't know how to make it work over the entire list. Any help would be greatly appreciated.

The entire solution must fit withing the reduce and I cannot import any other modules.

Solution

  • It can be done in two steps:

    1. sum consecutive items in the list: [sum(a[i:i+2]) for i in range(0, len(a), 2)]
    2. apply the reduction: reduce(lambda x, y: x * y, new_list)

    Compose them together:

    reduce(lambda x, y: x * y, [sum(a[i:i+2]) for i in range(0, len(a), 2)])