Implementing enumerate in forloop

Question

I recently learnt that the expression "in range(len(li)" is considered un-pythonic. So I read posts explaining that enumerate should be used instead. My question is how I could convert my current for loop (used for bubblesort) to enumerate correctly. My original loop looks like:

 a = [4,2,5,7,3,99,-2,8767,27,1]
 for j in range(len(a) - 1):

What I tried so far was:

for j, _ in enumerate(a) -1:

However this gave me the error: TypeError: unsupported operand type(s) for -: 'list' and 'int'

I noticed that this error has to do with the -1 since this is the only loop in my code that causes this problem.

You noticed your error, what are you asking/wanting? Fix the syntax and you have an iterable loop — ViaTech, May 17 '22 at 22:37
to iterative over a certain length, like `len(a) - 1`, you could use `itertools.islice(enumerate(a), len(a) - 1)` but this all depends on what you are trying to do — juanpa.arrivillaga, May 17 '22 at 22:37
In any case, we need to see the specific context to be better able to help. `range` might also be totally appropriate (seems reasonable for bubblesort) — juanpa.arrivillaga, May 17 '22 at 22:38

score 1 · Answer 1 · answered May 17 '22 at 22:38

It might help to see it this way:

If you only want each item:

>>> for item in a:
...     print(item)
... 
4
2
5
7
3
99
-2
8767
27
1

If you want an index as well:

>>> for index, item in enumerate(a):
...     print(index, item)
... 
0 4
1 2
2 5
3 7
4 3
5 99
6 -2
7 8767
8 27
9 1

Implementing enumerate in forloop

1 Answers1