pythonlistextend

Python: list.extend without mutating original variable

I am wondering whether there is a way in Python to use .extend, but not change the original list. I'd like the result to look something like this:

>> li = [1, 2, 3, 4]  
>> li
[1, 2, 3, 4]  
>> li.extend([5, 6, 7])
[1, 2, 3, 4, 5, 6, 7]  
>> li
[1, 2, 3, 4]

I tried to google this a few different ways, but I just couldn't find the correct words to describe this. Ruby has something like this where if you actually want to change the original list you'd do something like: li.extend!([5,6,7]) otherwise it would just give you the result without mutating the original. Does this same thing exist in Python?

Thanks!

Solution

  • The + operator in Python is overloaded to concatenate lists, so how about:

    >>> li = [1, 2, 3, 4]
>>> new_list = li + [5, 6, 7]
>>> new_list
[1, 2, 3, 4, 5, 6, 7]