Python lists

In Python, a list consists of:

• an ordered collection of items that can have different data types
• square brackets with items separated by commas

my_list = ['h', 90, True, 3.14, 'eX', False]

In that list, we notice that our collection includes a couple of strings, an int, a float and two Booleans!

List methods

Similar to strings, we can use some built-in methods to learn about a list:

my_list = ['h', 90, True, 3.14, 'eX', False]

# access individual items by index
print(my_list[1])
# 90

# slicing the list
print(my_list[3:5])
# [3.14, 'eX']

# finding the length of a list
print(len(my_list))
# 6

Changing list items

However, unlike strings, where we cannot changes individual characters, we can change individual list items:

my_list = ['h', 90, True, 3.14, 'eX', False]

# changing a list item by index
my_list[1] = 92
print(my_list)
# ['h', 92, True, 3.14, 'eX', False]

Adding and removing list items

We can also add items to and remove items from the list with the help three built-in methods for lists:

• append(item)
• remove(item)
• pop() and pop(atIndex)

my_list = ['h', 90, True, 3.14, 'eX', False]

# ==== USING append() ====

# adding list items with append
my_list.append('eX')
my_list.append(False)
my_list.append(2.718)

print(my_list)
# ['h', 90, True, 3.14, 'eX', False, 'eX', False, 2.718]

# ==== USING remove() ====

# remove the first item in the list 
# ...that contains 'eX'
my_list.remove('eX')

print(my_list)
# ['h', 90, True, 3.14, False, 'eX', False, 2.718]

# ==== USING pop() ====

# remove the last item from the list
my_list.pop()

print(my_list)
# ['h', 90, True, 3.14, False, 'eX', False]

# remove the item at the given index 
my_list.pop(1)

print(my_list)
# ['h', True, 3.14, False, 'eX', False]

Pay close attention to what the remove method does, as it doesn't remove all instances of what we feed into the argument!