Sequences of Data

CS 110

Sequences: Why are they useful?

• Allows us to store collections of data and allow us to easily read and process data via loops

​

• Examples:
• A sequence of notes for creating songs
• A sequence of colors to make a color palette
• A pair of coordinates (x,y)
• A sequence of coordinates to draw shapes (points, lines, polygons)
• A sequence of canvas objects that you can move and interact with
• ...

2

New Data Type (class): Tuple

• A tuple is an immutable sequence of values.
• Useful for organizing and conveniently accessing related data.
• In Python we define them like this:

tuple_of_strings = ("first year", "sophomore", "junior", "senior")�

​

4

New Data Type: Tuple

• A tuple is an immutable sequence of values.
• Useful for organizing and conveniently accessing related data.
• In Python we define them like this:

tuple_of_strings = ("first year", "sophomore", "junior", "senior")�

​

5

New Data Type: Tuple

• A tuple is an immutable sequence of values.
• Useful for organizing and conveniently accessing related data.
• In Python we define them like this:

tuple_of_strings = ("first year", "sophomore", "junior", "senior")�

​

6

Tuples: The Rules

A tuple is an immutable sequence of values:�

empty_tuple = ()

tuple_of_strings = ("first year", "sophomore", "junior", "senior")

​

• The items in a tuple can be of any type
• A tuple can be of any length
• You can access any tuple element through 0-based indexing
• You can slice tuples
• You cannot edit tuples (immutability)
• You can concatenate tuples to create new, longer tuples

7

What's the deal with…

immutability?

Data Types: Lists and Tuples

A list is a mutable sequence of values:�

empty_list = []

list_of_strings = ["first year", "sophomore", "junior", "senior"]

​

A tuple is an immutable sequence of values:�

empty_tuple = ()

tuple_of_strings = ("first year", "sophomore", "junior", "senior")

9

Lists: The Rules

A list is a mutable sequence of values:�

empty_list = []

list_of_strings = ["first year", "sophomore", "junior", "senior"]

​

• The items in a list can be of any type
• A list can be of any length
• You can access any list element through 0-based indexing
• You can slice a list
• You can edit a list (mutable)
• You can concatenate lists using the + operator
• You can sort lists (as long as Python knows how to sort your data)
• You can add elements to a list using the append function
• You can remove elements in a list using the pop function
• You can update specific elements in a list using the offset notation from #3.

Challenge Problem (03_quote_of_the_day.py)

See the file for details! (solution in the solutions folder)