1. 6. Lists Let's Learn Python and Pygame
Aj. Andrew Davison, CoE, PSU Hat Yai Campus
6. Lists
How to store data in lists.
A look at tuples and dictionaries.
What are mutable and immutable data types?

2. 1. Storing Lots of Data Together
Up to now we've stored 1piece of data in 1 variable:
x = 3
With bigger programs, it's useful if we can store lots of data inside 1 variable
we do this using a Python data structure
I'll look at 3 data structures:
lists, tuples, dictionaries

3. 2. The List
A list:
family = ["Mum", "Dad", "Brother", "Sister", "Baby"]
This stores 5 pieces of data in a list called family.
family
"Mum"
"Dad"
"Brother"
"Sister"
"Baby" 1 2 3 4
The boxes in a list are numbered
the numbers are called indexes (or indicies)
New boxes can be added; boxes can be deleted.

4. Adding Things to a List An empty list A list can store anything
friends
"like"
"hans solo" 1 2 3

5. Printing Parts of a List
The ":" is called
a slice.
friends
"like"
"hans solo" 1 2 3

6. Using Slice to Copy a List
friends
"like"
"hans solo" 1 2 3
copy a slice
numberFriends 1

7. Modifying Box Data

8. Other Ways to Add to a List
append() adds 1 item to the end of the list
seen already
extend() adds many items to the end of the list

9. insert() adds one item somewhere in the list
uses an index number
other boxes move to the right to make room
letters
"a"
"b"
"z"
"d"
"e"
"f"
"g"
"h" 1 2 3 4 5 6 7
letters
"a"
"b"
"y"
"z"
"d"
"e"
"f"
"g"
"h" 1 2 3 4 5 6 7 8

10. Deleting from a List Use: remove(), del(), or pop() letters letters
"b"
"y"
"z"
"d"
"e"
"f"
"g"
"h" 1 2 3 4 5 6 7 8
letters
"a"
"b"
"y"
"d"
"e"
"f"
"g"
"h" 1 2 3 4 5 6 7
The boxes move left
to fill the empty space.

11. letters letters The boxes move left to fill the empty space. 1 2 3 4 5
"d"
"e"
"f"
"g"
"h" 1 2 3 4 5 6 7
letters
"a"
"b"
"d"
"e"
"f"
"g"
"h" 1 2 3 4 5 6
The boxes move left
to fill the empty space.

12. letters letters letters 1 2 3 4 5 6 1 2 3 4 5 1 2 3 4 "a" "b" "d" "e"
"f"
"g"
"h" 1 2 3 4 5 6
letters
"a"
"b"
"d"
"f"
"g"
"h" 1 2 3 4 5
"e" x
letters
"a"
"b"
"d"
"f"
"g" 1 2 3 4
"h" x

13. Searching a List
Useful as a test in if's and while's

14. Lists and Loops
The counting loop can use a list:

15. Sorting Lists
The words list is changed.

16. The words list is
not changed. A new list
is created.

17. 3. Tuple: the Unchangeable List
Use (...) not [...]
Changes not
allowed. A tuple is
immutable.

18. This is allowed
since a new tuple
is being created.
tup is not changed.

19. 4. Dictionaries
A dictionary is a list where the index numbers are replaced by strings
the strings are called keys; data are called values
"Bob"
" "
"John"
" "
keys
"Mary"
" "
values
"Jenny"
" "

20. Building a Dictionary "Bob" "444-4321" "John" "555-1234" "Mary"
" "
"Jenny"
" "
A dictionary can store
key-value pairs in any
order it wants.

21. Accessing all the Keys / Values
Use the keys list
inside a for loop
Use a sorted keys list
to get values in key order

22. Deletion and Checking
Big "J" != "j"
Can only check
for keys