Practical Coding in Python

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Coding Exercises: Classes and Objects

Person

Write a Person class that includes the following:

• member variables for name and number of pets
• constructor taking name and number of pets as input
• member function greeting() that returns a string: “Hello, my name is (name) and I have (numberOfPets) pets.”

Write some test code that instantiates some Person objects and demonstrates that the functions are working properly.

ScoreKeeper

Write a ScoreKeeper class that includes the following:

• member variable to keep track of the score (initialized to 0)
• method scoreNormal() that adds 100 to the score
• method scoreBonus() that adds 1000 to the score

Write some test code that instantiates a ScoreKeeper object and tests its functions.

Magic Eight Ball

Write a MagicEightBall class that includes the following:

• a list of strings representing the possible replies
• member function ask() that takes a single string as input, ignores it, and returns a string randomly from the possible replies

Write some code that instantiates a MagicEightBall object and asks it some important questions.

Rectangle

Write a Rectangle class that includes the following:

• member variables for base and height
• constructor with base and height as inputs
• member function to return the area of the rectangle
• member function to return the perimeter of the rectangle
• member function to return the length of a diagonal of the rectangle

Write test code to demonstrate that your Rectangle class functions all work properly.

Bonus Challenge: Vector

Write a Vector class that represents a two-dimensional vector \(\vec{v} = \left<x, y\right>\).

Include the following:

• member variables for \(x\) and \(y\)
• constructor taking \(x\) and \(y\) as input
• member function that returns the magnitude of the vector
• member function that returns the direction of the vector (Note: this is a little tricky in general because you need to use atan() and check the quadrant. Fortunately, the math library includes a convenient function atan2(y, x) that does this check for you. Note that y comes before x.)
• member function that adds another vector to this one (like +=): add(u)
• member function that multiplies this vector by a scalar (like *=): scalarMultiply(k)
• member function that computes and returns the dot product of this vector with another vector: dotProduct(u)
• member function that calculates the angle between this and another vector: angle(u) Hint: Use what you know from pre-calculus, together with math.acos() and the dotProduct and magnitude functions above.

Be sure to write code to verify that your functions are all doing what they’re supposed to be doing.

Next: Appendix A: Virtual Environments and Libraries