What are some examples of using defaultdict in Python?

Can you explain what defaultdict is in Python?

Sure! defaultdict is a subclass of the built-in dict class. It overrides one method to provide a default value for a nonexistent key.

How do I create a defaultdict with a default value of 0?

You can create it like this: from collections import defaultdict; my_dict = defaultdict(int). This sets the default value to 0.

Can you give me an example of how to use defaultdict to count occurrences of items?

Absolutely! You can use it like this: from collections import defaultdict; counts = defaultdict(int); for item in ['apple', 'banana', 'apple']: counts[item] += 1. This will count the occurrences of 'apple' and 'banana'.

What happens if I try to access a key that doesn't exist?

If you access a nonexistent key, defaultdict will automatically create it with the default value you specified, like 0 in this case.