Key-ordered dict in Python

Question

I am looking for a solid implementation of an ordered associative array, that is, an ordered dictionary. I want the ordering in terms of keys, not of insertion order.

Answer 1

For "string to float" problem you can use a Trie - it provides O(1) access time and O(n) sorted iteration. By "sorted" I mean "sorted alphabetically by key" - it seems that the question implies the same.

Some implementations (each with its own strong and weak points):

• https://github.com/biopython/biopython has Bio.trie module with a full-featured Trie; other Trie packages are more memory-effcient;
• https://github.com/kmike/datrie - random insertions could be slow, keys alphabet must be known in advance;
• https://github.com/kmike/hat-trie - all operations are fast, but many dict methods are not implemented; underlying C library supports sorted iteration, but it is not implemented in a wrapper;
• https://github.com/kmike/marisa-trie - very memory efficient, but doesn't support insertions; iteration is not sorted by default but can be made sorted (there is an example in docs);
• https://github.com/kmike/DAWG - can be seen as a minimized Trie; very fast and memory efficient, but doesn't support insertions; has size limits (several GB of data)