A list is python's slice. It's a resizable array. Unlike most languages, elements do not need to all share the same type.

bicycles = ['trek', 'cannondale', 'redline', 'specialized']
print(bicycles[0])

length

The len() builtin returns the length of a list.

cars = ['bmw', 'audi', 'toyota', 'subaru']
print(len(cars))

checking that a list is not empty

An empty list returns false in an if statement.

requested_toppings = []
if requested_toppings:
    for requested_topping in requested_toppings:
        print(requested_topping)

accessing the last element

As a short-hand, rather than getting the length of the list, you can index using negative numbers. Using -1 will always return the last element of the list. However, an empty list will still print an error.

motorcycles = ['honda', 'yamaha', 'suzuki']
print(motorcycles[-1])

looping

Remember the colon:

magicians = ['alice', 'david', 'carolina']
for magician in magicians:
    print(magician)

numbers

The builtin range() function generates a list of numbers. Thus, creating a "traditional" for loop is as follows:

for value in range(1, 5):
    print(value) # 1 2 3 4

Note that the range is inclusive - exclusive. So 5 was not printed. The range function can accept other arguments if you need to loop over just even numbers or something.

In addition to range() there's also enumerate() if you need to index value:

animals = ["dog", "cat", "mouse"]
for i, value in enumerate(animals):
    print(i, value)

numbered list creation

You can also use the range syntax to create a list manually:

squares = [value**2 for value in range(1, 11)]

while loops

You can also make a while loop and break and continue do what you'd expect.

i = 1
while i <= 5:
    print(i)
    i += 1

in operator

There's a short-hand for checking if a value is in a list:

requested_toppings = ['mushrooms', 'onions', 'pineapple']
if 'mushrooms' in requested_toppings:
    print('yay mushrooms!')

To invert this use not in.

adding elements

Append to the end of a list.

motorcycles = ['honda', 'yamaha', 'suzuki']
motorcycles.append('ducati')

Insert at the start of the list (shifting other elements).

motorcycles = ['honda', 'yamaha', 'suzuki']
motorcycles.insert(0, 'ducati')

removing elements from a list

Using the del statement to remove at a certain index.

motorcycles = ['honda', 'yamaha', 'suzuki']
del motorcycles[0]

pop

motorcycles = ['honda', 'yamaha', 'suzuki']
last = motorcycles.pop()
print(last) # suzuki
print(motorcycles) # honda yamaha

by value

The remove methods deletes only the first occurrence of the value.

motorcycles = ['honda', 'yamaha', 'suzuki']
motorcycles.remove('honda')

copying

The slicing syntax is used to copy a list:

foods = ['pizza', 'falafel', 'carrot cake']
foods_copy = foods[:]

sorting

The sort() method is a quick way to sort a list (of strings) alphabetically. The method takes various arguments such as reverse=True. This modifies the list rather than making a copy.

cars = ['bmw', 'audi', 'toyota', 'subaru']
cars.sort()

The builtin function sorted() returns a copy of the list, having been sorted, without changing the original list.

cars = ['bmw', 'audi', 'toyota', 'subaru']
print(sorted(cars))

min and max

The builtin functions min() and max() operate on a list of numbers; returning the minimum or maximum value.

slicing

players = ['charles', 'martina', 'michael', 'florence', 'eli']
print(players[0:3]) // Prints elements 0, 1, and 2.