Swaping two elements in a list shows unexpected behaviour

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I have a list:

lis = [12,45,15,67,89]

I want to swap 12 and 89 such that the list should look

lis = [89,45,15,67,12]

When I do it this way

lis[0], lis[lis.index(89)] = lis[lis.index(89)], lis[0]

Nothing is changed

lis = [12,45,15,67,89]

But when I do it this way

lis5[0], lis5[4] = lis5[4], lis5[0]

It works perfect

lis = [89,45,15,67,12]

So why it isn't working the first way? PS-The whole reason I want to do the first way is because I want to find the max element in a list and then swap it with the first element of the list.

Something like:

max1 = max(lis)
lis[0], lis[lis.index(max1)] = lis[lis.index(max1)], lis[0]
python-3.x list arrays python
2 Answers

Just to extend the accepted answer, You can store using dict.

lis = [12,45,15,67,89]
new_list = []


dict = {k:v for (k,v) in enumerate(lis)}

    
dict[0], dict[4] = dict[4], dict[0]
    
for i in range(len(lis)):
    new_list.append(dict[i])
   
print(new_list)

And the way you were trying,

lis = [12,45,15,67,89]

lis[lis.index(89)], lis[0] = lis[0], lis[lis.index(89)]

print(lis)

both produces,

[89, 45, 15, 67, 12]

[Program finished]

Alternatively, for max values,

lis = [12,45,15,67,89]
max_index = lis.index(max(lis))
lis[0], lis[max_index] = lis[max_index], lis[0]
print(lis) 
user_130455080
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