# How to multiply all integers inside list

52

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]

This question is tagged with `python` `list` `multiplication` `scalar` `elementwise-operations`

89

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.

24

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))
``````