🐍 Lesson 8: Lists

A list colors holds "red", "green", "blue". Use a for loop to print each color on its own line.

colors = ["red", "green", "blue"]
for c in colors:
    print(c)

Start with cart = ["milk", "eggs"]. Add "bread" to the end, then print the whole list. Expected: ['milk', 'eggs', 'bread']

cart = ["milk", "eggs"]
cart.append("bread")
print(cart)

A list scores = [78, 100, 92, 45]. Print the highest score in the form: Highest score: 100. Use max() and an f-string.

scores = [78, 100, 92, 45]
print(f"Highest score: {max(scores)}")

Given nums = [10, 20, 30], print the average like Average: 20.0. Hint: average = sum(nums) / len(nums).

nums = [10, 20, 30]
average = sum(nums) / len(nums)
print(f"Average: {average}")

Make a list of your 3 favorite songs. Add one more, remove one, sort it, and print it after each change to watch it transform.

With animals = ["cat", "dog", "fox", "owl", "bee"], print: the first animal, the last animal (use [-1]), the first three as a list ([0:3]) and how many animals there are.

animals = ["cat", "dog", "fox", "owl", "bee"]
print(animals[0])
print(animals[-1])
print(animals[0:3])
print(len(animals))

Start with bag = ["apple", "pen"]. Append "book", insert "key" at position 0, remove "pen", then print the bag. Finally use .pop() to take out the last item, print the popped item, and print the bag again.

bag = ["apple", "pen"]
bag.append("book")
bag.insert(0, "key")
bag.remove("pen")
print(bag)
last = bag.pop()
print(last)
print(bag)

With nums = [5, 2, 9, 1]: print sorted(nums) (a sorted copy), then print nums to show the original is untouched. Then call nums.sort(reverse=True) and print nums — now it really changed.

nums = [5, 2, 9, 1]
print(sorted(nums))
print(nums)
nums.sort(reverse=True)
print(nums)

With votes = ["red", "blue", "red", "green", "red"], print: whether "blue" is in the list, how many votes "red" got (.count()), and the position of the first "green" (.index()).

votes = ["red", "blue", "red", "green", "red"]
print("blue" in votes)
print(votes.count("red"))
print(votes.index("green"))

Print a numbered menu from menu = ["pizza", "salad", "soup"] so it reads 1. pizza, 2. salad, 3. soup. Use for i, item in enumerate(menu, start=1):.

menu = ["pizza", "salad", "soup"]
for i, item in enumerate(menu, start=1):
    print(f"{i}. {item}")

From numbers = [4, 7, 10, 3, 8, 15], build a brand-new list called evens containing only the even numbers, then print it. Start with evens = [] and append inside a loop.

numbers = [4, 7, 10, 3, 8, 15]
evens = []
for n in numbers:
    if n % 2 == 0:
        evens.append(n)
print(evens)

A list comprehension does the last task in one line: [n * n for n in numbers]. From numbers = [1, 2, 3, 4, 5], print the squares in one line, then print only the odd numbers using [n for n in numbers if n % 2 == 1].

numbers = [1, 2, 3, 4, 5]
print([n * n for n in numbers])
print([n for n in numbers if n % 2 == 1])

A grid is a list of rows: grid = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]. Print the middle number (grid[1][1]), then print each row on its own line with the numbers separated by spaces.

grid = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(grid[1][1])
for row in grid:
    print(row[0], row[1], row[2])

You have players = ["Ana", "Ben", "Cy", "Dee"] and scores = [42, 91, 67, 88]. Print the top three, highest first, as 1. Ben - 91 and so on. Hint: list(zip(scores, players)) then sorted(..., reverse=True).

players = ["Ana", "Ben", "Cy", "Dee"]
scores = [42, 91, 67, 88]
board = sorted(zip(scores, players), reverse=True)
for i, pair in enumerate(board[:3], start=1):
    print(f"{i}. {pair[1]} - {pair[0]}")

Make a list of your ten favorite songs, games or foods. Print it numbered, print it sorted alphabetically, print how many items it has, then add one and remove one. 🎶