How Can I Create an Infinitely Nested defaultdict in Python?

Infinite-Level Nested Defaultdicts

Question

How can one create an infinitely nested defaultdict? In other words, is it possible to set the default value of a defaultdict to be another defaultdict? This would allow for arbitrary-depth nested structures that automatically create the necessary dictionaries as needed.

For example, consider the following code:

x = defaultdict(...stuff...)
x[0][1][0]
{}

In this scenario, x[0] would be a defaultdict, x[0][1] would be another defaultdict, and x[0][1][0] would be a standard dictionary.

Answer

While it's possible to create a defaultdict that contains other defaultdicts, it's not directly supported by the standard defaultdict arguments. However, there is a simple workaround that allows for multi-level nested defaultdicts.

Instead of defining the default value as another defaultdict, define the default value as a lambda function that returns a defaultdict:

x = defaultdict(lambda: defaultdict(dict))

This code creates a two-level defaultdict, where x[0] is a defaultdict and x[0][1] is another defaultdict, with values being dictionaries.

For infinite-level nesting, simply add additional levels to the lambda function:

x = defaultdict(lambda: defaultdict(lambda: defaultdict(...)))

This workaround enables the creation of arbitrarily nested defaultdicts, providing a convenient way to manage complex data structures with automatic value creation.

The above is the detailed content of How Can I Create an Infinitely Nested defaultdict in Python?. For more information, please follow other related articles on the PHP Chinese website!