Why does Python start at index -1 (as opposed to 0) when indexing a list from the end? [duplicate]

Answer 1

Because -0 in Python is 0.
With 0 you get first element of list and
with -1 you get the last element of the list

list = ["a", "b", "c", "d"]
print(list[0]) # "a"
print(list[-1]) # d

You can also think it as shorthand for list[len(list) - x] where x is the element position from the back. This is valid only if 0 < -(-x) < len(list)

print(list[-1]) # d
print(list[len(list) - 1]) # d
print(list[-5]) # list index out of range
print(list[len(list) - 5]) # a