Lists

A list in Python is a data type used to store a collection of objects.

Lists are always ordered and can contain different types of objects, such as strings, integers, booleans, etc. Lists are a mutable data type and therefore a good choice for dynamic data (adding and subtracting to lists).

Creating a List

There are multiple ways to define a list in Python. We can either assign a variable to a pair of square brackets ([]) with or without values, or we can assign a variable to the list() keyword and afterwords pass in its list items.

Defining empty lists:

list1 = []
list2 = list()

Creating lists with values in them:

list1 = ['one', 2, 'three']
list2 = [True, False, False, True, False]
list3 = [1, 2, 3, 4, 5, 6, 7, 8, 9]
list4 = ['one', 2, True]
list5 = ['one', 'two', 'three']

Using a Built-in List Method

friends = ['Sue', 'Bob']

print(type(friends))

# Use a built-in method to add Anna to the list of friends.
friends.append('Anna')

print(friends)

The output would be:

<class 'list'>
['Sue', 'Bob', 'Anna']

Lists

.append(): Adds an item to end of the list.
.clear(): Removes all items from the list.
.copy(): Returns a shallow copy of a list.
.count(): Searches a list for a particular item and returns the number of matching entries found.
.extend(): Adds list elements to end of the list.
.index(): Finds the first occurence of a particular value within the list.
.insert(): Adds an item at a specified index in the list.
.pop(): Removes an item from a list while also returning it.
.remove(): Removes an item from a list by passing in the value of the item to be removed as an argument.
.reverse(): Reverse the elements in the list.
.sort(): Sorts the contents of the list it is called on.