Quiz: Lambda with Map

map() is a higher-order built-in function that takes a function and iterable as inputs, and returns an iterator that applies the function to each element of the iterable. The code below uses map() to find the mean of each list in numbers to create the list averages. Give it a test run to see what happens.

Rewrite this code to be more concise by replacing the mean function with a lambda expression defined within the call to map().

Start Quiz:

numbers = [
              [34, 63, 88, 71, 29],
              [90, 78, 51, 27, 45],
              [63, 37, 85, 46, 22],
              [51, 22, 34, 11, 18]
           ]

def mean(num_list):
    return sum(num_list) / len(num_list)

averages = list(map(mean, numbers))
print(averages)

Quiz: Lambda with Filter

filter() is a higher-order built-in function that takes a function and iterable as inputs and returns an iterator with the elements from the iterable for which the function returns True. The code below uses filter() to get the names in cities that are fewer than 10 characters long to create the list short_cities. Give it a test run to see what happens.

Rewrite this code to be more concise by replacing the is_short function with a lambda expression defined within the call to filter().

Start Quiz:

cities = ["New York City", "Los Angeles", "Chicago", "Mountain View", "Denver", "Boston"]

def is_short(name):
    return len(name) < 10

short_cities = list(filter(is_short, cities))
print(short_cities)