nested_dict

Nested_dict is a powerful Python module designed to extend collections.defaultdict to create nested dictionaries of multiple levels on the fly. With this module, you can easily create nested dictionaries, even if they have not yet been declared. Auto-vivification, a process also known as "auto-creation," makes this possible. This feature can be a huge time-saver for those who regularly work with complex data structures.

Creating a nested_dict is straightforward. Once you have imported the module, you can declare the dictionary and its levels as follows:

nd = nested_dict()
nd["a"]["b"]["c"] = 311
nd["d"]["e"] = 311

Each time you access a nested level, it is created automatically. In the above example, accessing nd["a"]["b"]["c"] for the first time creates the dictionary {"a": {"b": {"c": 311}}}.

Nested_dict also extends collections.defaultdict beyond simple dictionary creation. You can create dictionaries of lists, sets, or other collections with a specified level of nesting using slightly different syntax.

First, you can use the old-fashioned way of creating a dictionary with ugly syntax:

d = dict()
d.setdefault("1st group", []).append(3)
d.setdefault("2nd group", []).append(5)
d.setdefault("2nd group", []).append(8)
d.setdefault("1st group", []).append(4)
d.setdefault("2nd group", []).append(5)

Alternatively, you can use the collections.defaultdict module for easy list creation:

from collections import defaultdict
dd = defaultdict(list)
dd["1st group"].append(3)
dd["2nd group"].append(5)
dd["2nd group"].append(8)
dd["1st group"].append(4)
dd["2nd group"].append(5)

Finally, you can create nested dictionaries that automatically create lists or other collections when required:

from nested_dict import nested_dict
nd = nested_dict(2, list)
nd["1st group"]["subset a"].append(3)
nd["2nd group"]["subset a"].append(5)
nd["2nd group"]["subset b"].append(8)
nd["1st group"]["subset a"].append(4)
nd["2nd group"]["subset b"].append(5)

By specifying two levels of nesting and a list object, we create nd as a nested dictionary of lists. Accessing the nested levels automatically creates the required lists. The resulting dictionary, as printed with print(nd), is:

{'1st group': {'subset a': [3, 4]}, '2nd group': {'subset b': [8, 5], 'subset a': [5]}}

Nested_dict also supports other collections, such as sets, with the same ease-of-use.

Other features of nested_dict include auto-vivification of nested dictionaries and the ability to specify a collection type at initialization.

In conclusion, nested_dict is a valuable addition to any Python developer's toolbox, providing powerful tools for the creation and manipulation of complex data structures.