Instance Variables - Lab

Introduction

In this lab, you'll practice using instance variables, which you use to store information about a particular instance object. You will continue to use our fuber theme and create some methods that operate on our instance variables to return some valuable information about the passenger and driver instance objects.

Objectives

In this lab you will:

• Define and call an instance method
• Define and access instance attributes

Define classes

Below, define classes for both the Driver and Passenger classes -- for now just define the classes and remember to include the keyword pass so that you'll have valid syntax for the classes.

# Driver class

# Passenger class

Next, instantiate a new instance of a passenger and a new instance of a driver. Give the passenger a rating of 4.9 and give the driver a miles_driven attribute of 100,000.

# Assign a driver instance
driver = None 

# Give the driver instance object 'miles_driven' of 100000

# Assign a passenger instance
passenger = None 

# Give the passenger instance object a 'rating' of 4.9

Search attributes using functions

Your next challenge is to build a function to find a driver with a given name. The function should take two inputs, drivers and search_names. drivers will be a list of driver objects (instances of the class you defined above) and search_name will be a string for the driver name you wish to search from.

The function should then return the first driver object from drivers whose name is an exact match to the search name. If there is no driver that matches the name searched for, then the function should return None and print a string stating "Sorry we couldn't find a driver with the name, ____! :(".

For example, if there were no results for the search name "Jack" your function should return None and print:

"Sorry, we couldn't find a driver with the name, Jack! :("

def find_driver_by_name(drivers, name):
    # Write your code here
    pass

To test your function, here are some arbitrary definitions to create instances of your Driver class. Run the cell below to load them into memory:

# Create drivers with relevant attributes
alex_driver = Driver()
alex_driver.name = "alex"
alex_driver.rating = 9.0

michelle_driver = Driver()
michelle_driver.name = "michelle"
michelle_driver.rating = 8.0

jake_driver = Driver()
jake_driver.name = "jake"
jake_driver.rating = 9.7

ashleigh_driver = Driver()
ashleigh_driver.name = "ashleigh"
ashleigh_driver.rating = 8.75

list_of_drivers = [alex_driver, michelle_driver, jake_driver, ashleigh_driver]

Use find_driver_by_name() along with list_of_drivers to check if the following drivers exist:

• "jake"
• "michelle"
• "allison"

# Find "jake"
output_1 = None
output_1

# Find "michelle"
output_2 = None
output_2

# Find "allison"
output_3 = None
output_3

If you correctly defined find_driver_by_name(), the first two calls should have returned Driver objects, while the third should have printed the apology statement and returned None. (You can further inspect the final output to verify this using the type() function which should reveal that the output is indeed a Nonetype).

While perhaps moderately useful, the function as written is rather brittle. Misspelling a driver's name will lead to no results. As such, write a more general function called name_starts_with() that will return a list of instance objects that start with a given substring.

# Write your function here that returns the list of 
# instance objects whose name starts with the given substring
def name_starts_with(drivers, substring):
    pass

Use name_starts_with() and list_of_drivers to find all drivers whose name start with 'a':

# Drivers whose name start with 'a'

Finally, define a function that returns the instance object of the driver with the highest rating:

# Write your function here that returns the driver with the highest rating
def highest_rated_driver(drivers):
    pass

Use this function to find the highest rated driver:

# Find the driver with the highest rating

Want more?

Define a NewDriver class with an instance method called passenger_names(). This method accesses the passengers attribute of the class and returns a list of all names associated with passengers.

# Define the NewDriver class

Before we proceed, run the following cell that creates four passenger objects and a list_of_passengers:

# Passengers 
alex_passenger = Passenger()
alex_passenger.name = "alex"

michelle_passenger = Passenger()
michelle_passenger.name = "michelle"

jake_passenger = Passenger()
jake_passenger.name = "jake"

ashleigh_passenger = Passenger()
ashleigh_passenger.name = "ashleigh"

list_of_passengers = [alex_passenger, michelle_passenger, jake_passenger, ashleigh_passenger]

Now, instantiate a NewDriver class called best_driver that has the attributes name, car_make, car_model, age, and passengers:

# Instantiate a NewDriver class object
best_driver = None 

# Add the name attribute and assign it 'Garol'


# Add the car_make attribute and assign it 'toyota'


# Add the car_model attribute and assign it 'camry'


# Add the age attribute and assign it 30


# Add the passengers attribute and assign it to list_of_passengers

Alright, great! Now you have some attributes on the driver that you can work with. Create an instance method in the NewDriver class called passenger_names which returns a list of all the passengers' names/ Your output should look like ['alex', 'michelle', 'jake', 'ashleigh'].

Well done! You have all the necessary information for your best_driver. In the previous cell, you assigned some passengers to this driver. What are their names?

# Find the names of the passengers
names_of_passengers = None 
print(names_of_passengers)

Summary

In this lab, you practiced creating instance variables that add information to our instance objects. You then used these instance methods to return information about the instances themselves.