Multi-Lookup-Dict

A dict-like container that allows multiple keys to address the same value.

Installation

pip install multilookupdict

Usage

>>> d = MultiLookupDict()
>>> d["a_key"] = "some_value"
>>> d.map_key("a_key", "another_key") # Make "another_key" an alias of "a_key"

Implemented as two dicts: - MultiLookupDict._data holds the 'canonical key' and value - MultiLookupDict._key_to_canonical_map maps 'alias keys' onto canonical keys. (Canonical keys are mapped to themselves in this dict)

Externally, all keys (canonical and alias) are treated identically, and all refer to the same value, unless a key is reassigned to another value using map_key.

Multi-key lookups and assignments

Iterables of keys can also be accessed, set, and mapped.

>>> d = MultiLookupDict()
>>> d[("key_a", "key_b", "key_c")] = "some_value"
>>> d["key_a"] == "some_value"

Where items are accessed with multiple keys, all distinct matching values are returned as a list (where multiple keys are requested, the result is always a list, for consistency)

>>> d["key_d"] = "some_other_value" # Add a distinct value
>>> d[("key_a", "key_b", "key_d")] == ["some_value", "some_other_value"]


>>> d.map_key("key_a", ("key_e", "key_f")) # Also do multiple mappings

To use a tuple as a single key, rather than a group of independent keys, make sure it is contained within another iterable, i.e. d[(("tuple_part1", "tuple_part2"),)] = "some value". Remember that when accessing this tuple-key, a list of items will be returned.

Methods

__setitem__(key/iterable_of_keys, value)

Sets a key to the value. If a (non-string) iterable is provided as key, each key will be assigned the value.

__getitem__(key/iterable_of_keys)

Gets a value from a key. If a (non-string) iterable is provided as a key, a list of distinct values matching all provided keys will be returned.

map_key(existing_key, new_key)

Assign the value of one key to another key. Both keys now point to the same value.

keys()

Returns all keys in MultiLookupDict. Returned keys refer to same or different objects.

values()

[Same as dict.values]

items()

Same as dict.items, except "key" part of the tuple is a set of keys for the corresponding value

pop(key)

Same as dict.pop. All keys pointing to value are removed.

aliases(key, omit_requested_key=False)

Returns all aliases of a given key, including the key provided. (Set omit_requested_key to True to exclude the provided key.)