How To Mutate A List With A Function In Python?
Here's a pseudocode I've written describing my problem:- func(s): #returns a value of s x = a list of strings print func(x) print x #these two should give the SAME output Whe
Solution 1:
func(s):
s[:] = whatever after mutating
return s
x = a list of strings
printfunc(x)print x
You don't actually need to return anything:
def func(s):
s[:] = [1,2,3]
x = [1,2]
printfunc(x)print x # -> [1,2,3]
It all depends on what you are actually doing, appending or any direct mutation of the list will be reflected outside the function as you are actually changing the original object/list passed in. If you were doing something that created a new object and you wanted the changes reflected in the list passed in setting s[:] =..
will change the original list.
Solution 2:
That's already how it behaves, the function can mutate the list
>>>l = ['a', 'b', 'c'] # your list of strings>>>defadd_something(x): x.append('d')...>>>add_something(l)>>>l
['a', 'b', 'c', 'd']
Note however that you cannot mutate the original list in this manner
defmodify(x):
x = ['something']
(The above will assign x
but not the original list l
)
If you want to place a new list in your list, you'll need something like:
defmodify(x):
x[:] = ['something']
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