Key-value

Definition

A key-value pair is a fundamental data structure used to store data, where each unique key maps to a specific value. In Python, dictionaries utilize key-value pairs for efficient data retrieval.

5 Must Know Facts For Your Next Test

1. A dictionary in Python is an unordered collection of key-value pairs.
2. Keys in a Python dictionary must be immutable types like strings, numbers, or tuples with immutable elements.
3. Values in a dictionary can be of any data type and can be duplicated.
4. Dictionary keys are case-sensitive and unique within the same dictionary.
5. The 'get()' method in dictionaries returns the value for a specified key if it exists; otherwise, it returns None or a default value.

Review Questions

• What types of objects can be used as keys in a Python dictionary?
• How do you access the value associated with a specific key in a Python dictionary?
• What happens if you try to retrieve a value using the 'get()' method with a non-existent key?

Related terms

Dictionary: An unordered collection of items where each item is stored as a pair consisting of a key and its corresponding value.

Immutable: An object whose state cannot be modified after it is created, such as strings and tuples.

get(): A method that retrieves the value for a specified key from the dictionary if it exists; otherwise, it returns None or an optional default value.