Introduction to Python

As you've probably noticed, dictionaries have unique characteristics that set them apart from lists and tuples. They also come with their own set of methods. Let's dive in.

• len(d) - returns the number of key:value pairs in the dictionary d.
• d.copy() - creates a copy of the dictionary d.
• d.items() - provides all the key, value pairs from the dictionary d.
• d.keys() - lists all the keys in the dictionary d.
• d.values() - provides all the values from the dictionary d.

Wondering how to add new entries to a dictionary? Dictionaries don't utilize list methods like .append() or .extend(), and they don't support concatenation like strings. Instead, since dictionaries organize data in key-value pairs, you simply assign values using keys:

• d[k] = e - assigns the value e to the key k. If the key k already exists in the dictionary, its associated value will be updated.

For example, let's add a couple of countries to our dictionary: