Dictionaries in Python are collections of key-value pairs that are unordered and can use different data types for keys. Keys provide access to their associated values and keys must be unique within a dictionary. Dictionaries allow modeling real-world things like chessboards or tic-tac-toe boards using nested dictionaries and lists.

1. Dictionaries in Python
Md. Shafiuzzaman
Lecturer, Dept. of CSE, JUST

2. The Dictionary Data Type
• A dictionary is a collection of many values
• Indexes for dictionaries can use many different data types
• Indexes for dictionaries are called keys
• A key with its associated value is called a key-value pair

3. Dictionaries vs. Lists
• Items in dictionaries are unordered
• Dictionaries can’t be sliced like lists

4. Example: birthday checker

5. The keys(), values(), and items() Methods

6. Covert to list

7. Assign key and value to separate variables

8. Checking Whether a Key or Value Exists in a
Dictionary
• Recall what we use in lists

9. Checking Whether a Key or Value Exists in a
Dictionary

10. The get() Method

11. The setdefault() Method

12. Exercise
• message = “As it is a rainy day, I like to enjoy kichuri and duck vuna”
• Write a program that loops over each character in the message
variable’s string to count how often each character appears

13. Count how often each character appears in
message

14. Pretty Printing
• import the pprint module into your programs

15. Using Data Structures to Model Real-World
Things
• Chessboard
• Tic-Tac-Toe Board

16. Tic-Tac-Toe Board

17. Tic-Tac-Toe Board

18. Tic-Tac-Toe Board

19. Tic-Tac-Toe Board

20. Tic-Tac-Toe Board

21. Tic-Tac-Toe Board

22. Tic-Tac-Toe Board

23. Nested Dictionaries and Lists