Lab 07

Classes

1 Today

1. Classes
2. In class exercise

2 Recap: Classes

What are classes? What are some important elements to remember when making a class?

Recall this class we introduced a couple of week ago:

import statistics

class Student:
    """Student class definition"""
    
    def __init__(self, name: str):
        """Student class constructor"""
        self.name = name  # Student class properties
        self.grades = []
        
    # Student class methods
    def take_class(self, grade: float):
        self.grades.append(grade)
        
    def gpa(self) -> float:
        return statistics.mean(self.grades)

romi = Student("Romi")

print(romi.name)
print(romi.grades)

Romi
[]

romi.take_class(3.5)

print(romi.grades)

[3.5]

2.1 Discussion

1. Say I want make a class on information that a song may contain. How would I make a class Song(), that contains the name of the song, the artist of the song, the genres of the song, and the year it was released?

2. For example, make a variable down_under which has the following information: - Name: "Down Under" - Artist: "Men at Work" - Genre: ["Pop", "Rock"] - Year: 1981

Expected output:

down_under = Song("Down Under", "Men at Work", ["Pop", "Rock"], 1981)

down_under.name

'Down Under'

down_under.artist

'Men at Work'

down_under.genre

['Pop', 'Rock']

down_under.year

1981

How do I add a new method to the Class, which adds a new genre to it?

For example:

down_under = Song("Down Under", "Men at Work", ["Pop", "Rock"], 1981)

down_under.add_genre("Classic Rock")

down_under.genre

['Pop', 'Rock', 'Classic Rock']

3 In Class Exericses

Make a class Cat which contains a cat’s name, color, and its average walking speed (speed, in feet/second. The average walking pace of a cat is around 4 feet per second).

For example:

mittens = Cat("Mittens", "brown", 4)

mittens.name

'Mittens'

mittens.color

'brown'

mittens.speed

4

Add a method: Make a new method meow that takes an int and prints out that number of meows. Hint: Use a for loop.

mittens.meow(5)

Meow!
Meow!
Meow!
Meow!
Meow!

Challenge! Make a method move() in your Cat class that takes a distance (int) in feet as input, and prints out how long it took for your cat to travel that distance. Recall from high school math that \(time = \frac{distance}{speed}\)

For example:

mittens.move(30)

It took Mittens 7.5 seconds to travel 30 feet.