On 29 Jul, 03:47, Navkirat Singh <navkir...@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). Those are different data structures. The main things to note is that: - Access is best-case O(1) for the hash table and O(log n) for the BST. - Worst case behavior is for access is O(n) for both. The pathologic conditions are excessive collisions (hash) or an unbalanced tree (BST). In pathologic cases they both converge towards a linked list. - Searches are only meaningful for == and != for a hash table, but BST searches are also meaningful for >, <, <=, and >=. For this reason, databases are often implemented as BSTs. - A BST can be more friendly to cache than a hash table, particularly when they are large. (Remember that O(1) can be slower than O(log n). Big-O only says how run-time scales with n.) That said, I have not compared ordered dicts with normal dicts, as I still use 2.6. -- http://mail.python.org/mailman/listinfo/python-list
