how to multiply,divide,add and subtract from every member of a list

Question

If I had a list such as: my_list = [1,2,3] how do I multiply every member in the list by 2 so that the new list would be [2,4,6]

Answer 1 · 2018-01-13T03:32:21Z

January 13, 2018 3:32am

There's several ways to do this — for one, you could simply use a loop:

new_list = []
for i in my_list:
    new_list.append(i*2)

But there's a function called "map" that's perfectly suited for this kind of task:

new_list = list(map(lambda x: x*2, my_list))

Answer 2 · 2018-01-13T08:31:14Z

January 13, 2018 8:31am

# don't forget about using list comprehension
>>> my_list = [1,2,3]
>>> new_list = [x*2 for x in my_list]
>>> new_list
[2, 4, 6]

# to change *in-place*
>>> for idx in range(len(my_list)):
...     my_list[idx] *= 2
...
>>> my_list
[2, 4, 6]

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Jacob Roff

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how to multiply,divide,add and subtract from every member of a list

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