insert() but with negative index

insert() but with negative index - Printable Version

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insert() but with negative index - naughtysensei - Oct-01-2020

Inserting items with non-negative index gives expected results:

num = [1, 2, 3]
num.insert(0, "min")
print(num)

Output:
['min', 1, 2, 3]

but with negative index, as in this case shouldn't "max" be inserted at last index

num.insert(-1, "max")
print(num)

Output:
['min', 1, 2, 'max', 3]

I mean its not wrong its how they made python to work but why would they do so or am being stupid here?

RE: insert() but with negative index - micseydel - Oct-01-2020

Your confusion makes sense. It took me a moment to realize it too. You're thinking that it inserts intp the index you provide. This is not quite correct.

https://docs.python.org/3.8/tutorial/datastructures.html (emphasis added) Wrote:Insert an item at a given position. The first argument is the index of the element before which to insert, so a.insert(0, x) inserts at the front of the list, and a.insert(len(a), x) is equivalent to a.append(x).

Given this, the behavior makes sense: -1 is the index of the last element, so you insert before it.