Python indexing problem

Question

I don't understand how the following code works, could someone explain how it is assigning elements to the list?

lst = [1,2,3,4,5]
for i in range(1,6):
lst[i:i] = [i]
print(lst)

https://code.sololearn.com/c3tdEklK3II1

Answer 1

Edward Finkelstein ,

what we have here is a slice on the left side of the expression, this is called slice assignment. just have a look at this line:

lst[i:i] = [i]

it means that the value of 'i' that is coming from the range object will be inserted at the lst[i:i] position. existing values are not overwritten but they will be moved to the right. for this case you can think about list.insert(). both codes give the same result

lst = [1,2,3,4,5]
for i in range(1,6):
lst[i:i] = [i]
print(lst)

lst = [1,2,3,4,5]
for i in range(1,6):
lst.insert(i,i)
print(lst)

for more information have a look here:
https://prosperocoder.com/posts/JUMP_LINK__&&__python__&&__JUMP_LINK/slice-assignment-in-python/
>>> watch also the video on this webpage, it demonstrates the use with some samples.

Answer 2

[i:i] is an empty list .
Read it as the list between lst[i] and lst[i+1]
Yeah... there is..... nothing.
This nothing will be replaced by a list [i].

Answer 3

https://stackoverflow.com/questions/10623302/how-does-assignment-work-with-list-slices

Answer 4

It appears to be slicing by the numbers in the list, sequentially... And placing a sequential number in while pushing the rest back.

The initial element of a list is list_name[0]

So the 1 is untouched... But a 1 is placed afterward... After the first slice.

Then slice at list[2] drop in the 2... Then slice at list[3] drop in 3... As it iterates.

1, (1, 2, 3, 4, 5), 2, 3, 4, 5

Answer 5

Hi,
This code shows how to populate the list wih whatever values. I hope it helps

lst = [1,2,3,4,5]
for i in range(5):
lst[i] = i+5
print(lst)

Answer 6

For slicing,
lst = [1,2,3,4,5]
for i in range(1,5):
lst[i:i+4] = [i+1]
print(lst)