+ 4
Python indexing problem
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
6 Respostas
+ 6
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.
+ 7
[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].
+ 3
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
+ 2
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)
+ 2
For slicing,
lst = [1,2,3,4,5]
for i in range(1,5):
lst[i:i+4] = [i+1]
print(lst)