IndexedDicts

IndexedDict is an ordered mapping whose elements can be accessed using index, in addition to key. The interface is mostly a generalization of collections.OrderedDict.

Differences from OrderedDict

Methods get, pop and move_to_end have a different signature from OrderedDict, allowing exactly one of index or key argument to be used. This causes the IndexedDict to not be a drop in replacement to OrderedDict.

New Methods

fast_pop
Remove an item with given key and value from the IndexedDict by first swapping the item to the last position and then removing it. Returns tuple of (popped_value, new_moved_index, moved_key, moved_value). Time complexity of this operation is O(1).
index
Return index of a record with given key.
key
Return key of a record at given index.

Time Complexity

IndexedDict generally combines time complexity of dict and list. Indexed lookups cost list’s O(1), keyed lookups cost average case O(1) and worst case O(n) of dict. Deleting an element has a time complexity of O(1) if it is the last added one, or O(n) in general, in addition to the lookup cost.

API

class collections_extended.IndexedDict(iterable=None, **kwargs)[source]

A Mapping that preserves insertion order and allows access by item index.

The API is an extension of OrderedDict.

__init__(iterable=None, **kwargs)[source]

Create an IndexedDict and initialize it like a dict.