As I can see, pathlib path parents don't support slicing with negative indexes: 

>>> import pathlib
>>> path = pathlib.PosixPath("some/very/long/path/here")
>>> path.parents[-1]
...
    raise IndexError(idx)
IndexError: -1

That's kinda weird for python. I mean, in regular list/etc if I need the last element, I'd normally do list[-1], but here to get the last parent, I need to actually know how many parents do I have. 

So now, I can do something like this:

>>> parents_count = len(path.parents) - 1
>>> path.parents[parents_count]
PosixPath('.')

So that's how I can get the last parent. But is it pythonic? No.

So, I decided to fix this, and now we can do negative slicing:

>>> path.parents[-1] == path.parents[parents_count]
True
>>> path.parents[-2] == path.parents[parents_count - 1]
True

So what do you guys think about this?

Here's opened PR: https://github.com/python/cpython/pull/21799

This is a duplicate of 21041, it would be better to change the title of your PR so that it points to this bug report and to continue the discussion there.

*This is a duplicate of issue 21041

Closing it as duplicate of issue21041. Thanks Remi. Yaroslav, feel free to discuss it in the other issue.

superseder: pathlib.PurePath.parents rejects negative indexes

nosy: + xtreak
messages: + msg375093
resolution: duplicate
stage: patch review -> resolved

messages: + msg375082
versions: - Python 3.5, Python 3.6, Python 3.7, Python 3.8, Python 3.9

pull_requests: + pull_request20934
stage: patch review