mikeappell/introduction-to-functions-lab-data-science-alpha

Functions lab

As we know, we can use functions to give a name to sequences of our code, to make it more expressive. We can also use functions to allow us to reuse code. In this lab we will get practice in using functions for these purposes.

Objectives

• Practice declaring and returning values from function
• Practice accessing variables outside of a function's scope, from inside of a function

Writing our first functions

Imagine we work in a diner. We have a list of orders which we assign below. Write a function called number_of_orders that returns the current number of orders.

orders = ['turkey sandwich', 'eggs']
def number_of_orders():
    pass

number_of_orders() # 2

Now write another function called next_up that returns the first order (the order with the lowest index), in the orders list.

def next_up():
    pass

orders = ['turkey sandwich', 'eggs']
next_up() # 'turkey sandwich'

orders = ['beet salad', 'fennel']
next_up() # 'beet salad'

Ok, now write a function called healthy_order that returns the string 'spinach salad'.

def healthy_order():
    pass

healthy_order() # 'spinach salad'

Now let's declare an array called orders. Change the function healthy_order so that it continues to return the string 'spinach salad', but also adds the string 'spinach salad' to the end of the list of orders.

orders = ['turkey sandwich', 'eggs']
healthy_order()
orders[-1] # 'spinach salad'

'eggs'

Now let's write another function iterates through the list of orders and capitalizes the first letter of each word in the order. It should return a list of capitalized orders.

orders = ['spinach salad', 'turkey sandwich']
def capitalize_orders():
    pass

capitalize_orders() # ['Spinach Salad', 'Turkey Sandwich']

Now if someone adds, an upcapitalized order, we can simply call our function again to return a list of capitalized orders.

orders = ['spinach salad', 'turkey sandwich']
capitalize_orders() # ['Spinach Salad', 'Turkey Sandwich']
orders.append('eggs')
capitalize_orders() # ['Spinach Salad', 'Turkey Sandwich', 'Eggs']

Summary

Great job. Through this lab you were able to get practice both writing and returning values from functions. You also practiced accessing variables not local to the function, but in the global scope.