Performance ordered dictionary vs normal dictionary

[Hrvoje Niksic]

sturlamolden <sturlamolden at yahoo.no> writes:

> On 29 Jul, 03:47, Navkirat Singh <navkir... at gmail.com> wrote:
>
>> I was wondering what would be better to do some medium to heavy book keeping in memory - Ordered Dictionary or a plain simple Dictionary object??
>
> It depends on the problem. A dictionary is a hash table. An ordered
> dictionary is a binary search tree (BST).

The ordered dictionary shipped with Python is also a hash table, with an
internal list to keep track of item order.

The one thing not mentioned in the thread is that ordered dict's
deletion is O(n), which might impact "heavy bookkeeping".  As Raymond
said, where order doesn't matter, it's best to stick with dict.