On Mon, Aug 31, 2020 at 9:30 PM <junkneno...@gmail.com> wrote: > I have a use case which relates to this request: iterating over a dict > starting from a given key. I would like to achieve this without having to pay > the full O(n) cost if I'm going to be iterating over only a few items. My > understanding is that this should be achievable without needing to iterate > through the entire dict, since the dict's internal key lookup points to a > particular index of dk_entries anyway. > [snip] > Doing this efficiently would require either the addition of indexing to dicts > as well as some sort of get_key_index operation, or else could be done > without knowing indices if an iter_from_key operation were introduced (which > used the internal dk_indices to know where to start iterating over > dk_entries). I think this thread touches on the same sorts of debates however > so I'm mentioning this here. >
Note that proposed index access is O(n), not O(1). So `get_key_index` doesn't match your use case. On the other hand, iter_from_key is possible idea. Another API idea is `d.next_item(key)` and `d.prev_item(key)`. They return None if the key is left/right end. They raise KeyError if key not found. Other wise, they return (key, item) pair. > I also think that even if adding new features to the built-in dict is > undesirable, adding a collections.IndexableDict would be very useful > (sortedcollections.IndexableDict exists but sorting is not acceptable for > many use cases). Maybe, OrderedDict can have od.next_item(key) and od.prev_item(key). Regards, -- Inada Naoki <songofaca...@gmail.com> _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/2BIYAHUZTPRR5P6Y3MDVFBVY7PEECEDE/ Code of Conduct: http://python.org/psf/codeofconduct/
