python list multiply each value

Question

I wonder how can I multiply each element in two different lists.

For example :

list_a = [1,2,3,4,5] list_b = [10,20,30,40,50]

I want to make it 1X10 2X20 3X30 4X40 5X50

so that the result will be 10, 40, 90, 160, 250

I would really appreciate if you can help me.

Possible duplicate of [How do I multiply each element in a list by a number?](https://stackoverflow.com/questions/35166633/how-do-i-multiply-each-element-in-a-list-by-a-number) — Nick Brady, Aug 04 '17 at 05:24
`zip` in best method for this.[zip](https://docs.python.org/3.3/library/functions.html#zip) — Rohit-Pandey, Aug 04 '17 at 22:10

score 3 · Answer 1 · answered Aug 04 '17 at 06:21

3

You can use zip function as below.

>>> list_a = [1,2,3,4,5]
>>> list_b = [10,20,30,40,50]
>>> [(x[0]*x[1]) for x in zip(list_a,list_b)]
[10, 40, 90, 160, 250]

answered Aug 04 '17 at 06:21

voidpro

2

`[a*b for a,b in zip(list_a,list_b)]` would be a little neater – Chris_Rands Aug 04 '17 at 12:14
or `list(map(operator.mul, list_a, list_b))` – Chris_Rands Aug 04 '17 at 12:16

score 1 · Answer 2 · answered Aug 04 '17 at 09:32

1

Using zip():

list_a = [1,2,3,4,5]
list_b = [10,20,30,40,50]
final = [k*v for k, v in zip(list_a, list_b)]
print final

Output:

[10, 40, 90, 160, 250]

answered Aug 04 '17 at 09:32

Chiheb Nexus

For Python 3 you need to put `k,v` in parenthesis like this : `(k,v)`. Final line is `final = [k*v for (k, v) in zip(list_a, list_b)]`. – Zcode Aug 04 '17 at 11:44
1

Sorry, you're right. Python 3 documentation said that parenthesis were needed but it's only the return part of the comprehension list. – Zcode Aug 04 '17 at 11:56

Badri Gs · Answer 3 · 2017-08-05T04:32:33.990

0

a = [1,2,3,4,5] 
b = [10,20,30,40,50]
print [a[i]*b[i] for i in range(len(b))]

This will helpful for you

edited Aug 05 '17 at 04:32

answered Aug 04 '17 at 05:34

Badri Gs

You forgot to return their product! – Ubdus Samad Aug 04 '17 at 06:12
i will understand question wrongly now i will change the output – Badri Gs Aug 04 '17 at 12:09
Why `str` used in your solution.@adchoi_97 want `integer` item in list not `string`. – Rohit-Pandey Aug 04 '17 at 22:12

score 0 · Answer 4 · answered Aug 04 '17 at 09:28

0

a = [1,2,3,4,5]
b = [i*i*10 for i in a]

answered Aug 04 '17 at 09:28

Devaraj Phukan

Ubdus Samad · Answer 5 · 2017-08-04T12:32:31.723

-1

A cleaner version would be :

a,b = [1,2,3,4,5],[10,20,30,40,50]
for i,j in zip(a,b):
    print '%d x %d = '%(i,j),'%d units'% ((i*j))

edited Aug 04 '17 at 12:32

answered Aug 04 '17 at 06:10

Ubdus Samad

1

you should use `zip` instead of `map` – juanpa.arrivillaga Aug 04 '17 at 06:16
Can you explain what difference does it makes? I mean does it saves computing time or what? – Ubdus Samad Aug 04 '17 at 06:18
1

That `map` is meant for *mapping operations* and `zip` is meant for zipping. You are using `zip` to do mapping. It is simply bad form. – juanpa.arrivillaga Aug 04 '17 at 06:19
You don't need the `None` argument, just `zip(a, b)` – juanpa.arrivillaga Aug 04 '17 at 06:21
Yeah, i checked! – Ubdus Samad Aug 04 '17 at 06:22

5 Answers5