A dict-like container that allows multiple keys to address the same value.
Project description
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 aset
of keys for the corresponding value pop(key)
-
- Same as
dict.pop
. All keys pointing to value are removed. - Same as
aliases(key, omit_requested_key=False)
- Returns all aliases of a given key, including the key provided. (Set
omit_requested_key
toTrue
to exclude the provided key.)
Project details
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