Swap elements within a list

Question

def swap(x, y):
     mylist[x] = mylist[y]

mylist = ["a", "b", "c", "d"]

swap(2, 3)
print(mylist)

So i need to swap two elements in the list with each other but in my code it only replaces not swap. for example it will output as "a b d d" when it shouldn't repeat the same letter twice. it should output as "a b d c" Any helpers?

score 1 · Accepted Answer · answered Oct 07 '21 at 23:35

1

You can swap tuples in one step with:

def swap(x, y):
     mylist[x], mylist[y] = mylist[y], mylist[x]

mylist = ["a", "b", "c", "d"]

swap(2, 3)
print(mylist)
# ['a', 'b', 'd', 'c']

answered Oct 07 '21 at 23:35

Mark

90,562
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score 0 · Answer 2 · answered Oct 07 '21 at 23:34

0

You are never updating mylist[y]. You should run

def swap(x,y):
   assert(x < len(mylist) and y < len(mylist))
   temp = mylist[x]
   mylist[x] = mylist[y]
   mylist[y] = temp

answered Oct 07 '21 at 23:34

M. Chak

530
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13

score 0 · Answer 3 · answered Oct 07 '21 at 23:43

You just need to swap the value on the given index, as of now you are doing assignment :-

mylist[x] = mylist[y]

Which is wrong. You are replacing the value of x index with Y index

Correct swap :-

def swap(x,y):
   assert(x < len(mylist) and y < len(mylist))
    mylist[x], mylist[y] = mylist[y], mylist[x]

Swap elements within a list

3 Answers3