CODEWITHSUNDEEP
pythonpython-3.xlambdalist-comprehension
coderfrombiz
coderfrombiz

Reputation: 137

How to multiply a zipped list's items with eachother?

I'm doing an exercise where I create a function that receives two lists and returns the multiplications of the items at the same indices in a separate single list. Example:

transform("1 5 3", "2 6 -1")
#should return
[2, 30, -3]

To be clear, the program takes the items at index 1, 2 and 3 and multiplies them like this:

(1 * 2), (5 * 6), (3 * -1)

Now, the problem I face is that it is a must to use zip() function in the program, which I have not properly used yet.

I have made a program that does the general task successfully, but I can't figure out a solution that would use a zipped list. Could anyone help me with this? I have an idea that I could use the zipped list "q" that I have created within the map() function, but I don't know how.

Here is my program:

def transform(s1, s2):
    i = 0

    s = s1.split(' ')
    d = s2.split(' ')

    while i < len(s):
        try:
            s[i] = int(s[i])
            d[i] = int(d[i])
            i += 1
        except ValueError:
            break

    print(s, d)

    q = list(zip(s, d))
    print(q)

    final = list(map(lambda x, y: x * y, s, d))

    return final

def main():
    print(transform("1 5 3", "2 6 -1"))

if __name__ == "__main__":
    main()

Thank you in advance to anyone that helps!

Upvotes: 3

Views: 416

Answers (4)

hiro protagonist
hiro protagonist

Reputation: 46921

this should do what you want:

def transform(a, b):
     return [int(i) * int(j) for i, j in zip(a.split(), b.split())]



a = "1 5 3"
b = "2 6 -1"
print(transform(a, b))  # [2, 30, -3]

the use of split and zip should be straightforward. then a list comprehension creates the list.

Upvotes: 3

Ironkey
Ironkey

Reputation: 2607

try this out

item1, item2 =  "1 5 3", "2 6 -1"

def transform(i1, i2):
    return [int(x) * int(y) for x, y in zip(i1.split(" "), i2.split(" "))]

print(transform(item1, item2))

Upvotes: 1

azro
azro

Reputation: 54168

  1. To easily transform one string into a list of string you use map

    s = "1 2 3"
list(map(int, s.split())) 
> [1, 2, 3]

  2. Then you zip the 2 lists

    zip(map(int, s1.split()), map(int, s2.split()))
> [(1, 2), (5, 6), (3, -1)]`

  3. Finally you want to apply lambda x: x[0] * x[1] to each pair, or operator.mul(x[0], x[1])

from operator import mul

def transform(s1, s2):
    return list(map(lambda x: mul(*x), zip(map(int, s1.split()), map(int, s2.split()))))

Upvotes: 2

Chris
Chris

Reputation: 16172

s1 = '1 5 3'
s2 = '2 6 -1'

def transform(s1, s2):
    return [x*y for x,y in zip([int(x) for x in s1.split()],
                               [int(x) for x in s2.split()])]

transform(s1,s2)

Output

[2, 30, -3]

Upvotes: 1

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