[Tutor] append vs list addition

[Peter Otten]

C Smith wrote:

> I meant for example:
> list1 = [1,2,3]
> list2 = [3,4,5]
> 
> newList = list1 + list2
> 
> versus
> 
> for x in list2:
>    list1.append(x)
> 
> Which is the preferred way to add elements from one list to another?

None of the above unless you need to keep the original list1. Use

list1.extend(list2) # 1

or

list1 += list2 # 2

I prefer (1), but both do the same under the hood: append all items from 
list2 or any iterable to list1.


If you want to preserve the original list1

new_list = list1 + list2

is fine.