How to multiply all integers inside list

Hello so I want to multiply the integers inside a list.

For example;

l = [1, 2, 3]
l = [1*2, 2*2, 3*2]

output:

l = [2, 4, 6]

So I was searching online and most of the answers were regarding multiply all the integers with each other such as:
[1*2*3]

Answers:

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Method 1

Try a list comprehension:

l = [x * 2 for x in l]

This goes through l, multiplying each element by two.

Of course, there’s more than one way to do it. If you’re into lambda functions and map, you can even do

l = map(lambda x: x * 2, l)

to apply the function lambda x: x * 2 to each element in l. This is equivalent to:

def timesTwo(x):
    return x * 2

l = map(timesTwo, l)

Note that map() returns a map object, not a list, so if you really need a list afterwards you can use the list() function afterwards, for instance:

l = list(map(timesTwo, l))

Thanks to Minyc510 in the comments for this clarification.

Method 2

The most pythonic way would be to use a list comprehension:

l = [2*x for x in l]

If you need to do this for a large number of integers, use numpy arrays:

l = numpy.array(l, dtype=int)*2

A final alternative is to use map

l = list(map(lambda x:2*x, l))

Method 3

Another functional approach which is maybe a little easier to look at than an anonymous function if you go that route is using functools.partial to utilize the two-parameter operator.mul with a fixed multiple

>>> from functools import partial
>>> from operator import mul
>>> double = partial(mul, 2)
>>> list(map(double, [1, 2, 3]))
[2, 4, 6]

Method 4

The simplest way to me is:

map((2).__mul__, [1, 2, 3])

Method 5

using numpy :

    In [1]: import numpy as np

    In [2]: nums = np.array([1,2,3])*2

    In [3]: nums.tolist()
    Out[4]: [2, 4, 6]

Method 6

#multiplying each element in the list and adding it into an empty list
original = [1, 2, 3]
results = []
for num in original:
    results.append(num*2)# multiply each iterative number by 2 and add it to the empty list.

print(results)

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0