Solution Example

This is an example of how to write a tutorial that includes solutions

sorted() is a function that can be used to sort a list of items:

nums = [5, 3, 8, -23, 11, 2, 1]
sorted(nums)

The reverse flag can be used to sort the items in descending order:

sorted(nums, reverse=True)

Of course this function can be used to sort more than just numbers:

fruit = ["cherry", "apple", "kiwi", "orange", "strawberry", "banana"]
sorted(fruit)

It’s even possible to provide a custom function to specify the criteria by which you want the items sorted. For example, instead of sorting fruit alphabetically, we can sort them by the number of characters in their name:

sorted(fruit, key=len)

Exercises

Test your understanding with the following excercises

Exercise 1

Sort the list of fruit, by the number of characters in their name in descending order

Solution (click to reveal)

sorted(fruit, key=len, reverse=True)

Exercise 2

Sort the list of fruit, by the number of vowels in their name in ascending order

Solution (click to reveal)

To solve this, we need to write a function that takes a string and returns the number of vowels in that string. We can then pass it to the key parameter of the sorted function to set the sort criteria.

We can use a list comprehension to get a list of the vowel characters in a string [c for c in 'string' if c in 'aeiou']. From there we can use len to count them and we get our solution:

def num_vowels(name: str) -> int:
    return len([c for c in name if c in 'aeiou'])

sorted(fruit, key=num_vowels)

Exercise 3

Given the following list of tuples, representing fruit and their corresponding cost, sort them from most to least expensive:

fruit = [("cherry", 0.2), ("apple", 1.2), ("kiwi", 2.5), ("orange", 2), ("strawberry", 0.5), ("banana", 1.8)]

Solution (click to reveal)

def get_price(item: tuple) -> int:
    return item[1]

sorted(fruit, key=get_price, reverse=True)