Modules in Python: defaultdict

photo by vishnoi

Let’s discover defaultdict and its functions.

We’ll cover the following

• Overview of defaultdict
• Simple example of counting the occurrence of words
• Trying Python list type as default_factory
• Using lambda as default_factory

Overview of defaultdict

The collections module has a handy tool called defaultdict. The defaultdict is a subclass of Python’s dict that accepts a default_factory as its primary argument. The default_factory is usually a Python type, such as int or list, but we can also use a function or a lambda.

Simple example of counting the occurrence of words

Let’s start by creating a regular Python dictionary that counts the number of times each word is used in a sentence:

Once again, this cuts out the if/else conditional logic and makes the code easier to follow.

Using lambda as default_factory

This is some pretty cool stuff! Let’s go ahead and try using a lambda too as our default_factory!