Programming · StudentHub Lesson

Lists & Arrays

Learn how to store and manipulate collections of data using lists in Python.

18 minBeginner

What you will learn

Create and access elements in a Python list
Use indexing to retrieve list items
Add and remove items from a list
Loop through a list using a for loop
Understand list length and common list methods

Watch the lesson

Python for Beginners – Full Course [Programming Tutorial] · freeCodeCamp.org

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Topic notes

Main Idea

Lists (arrays) let programs store multiple values together in a single ordered collection.

Key Concepts

Lists are created with square brackets
Items are accessed using zero-based indexing
Lists are mutable: you can add, remove, or change elements
Loops are commonly used to process every item in a list

Definitions

List: an ordered, mutable collection of items
Index: the position of an item in a list, starting at 0
Method: a built-in function associated with a data type, like append()

Syntax

```python

fruits = ["apple", "banana", "cherry"]

print(fruits[0]) # apple

fruits.append("date") # add item

fruits.remove("banana") # remove item

for fruit in fruits:

print(fruit)

```

Examples

len(fruits) returns the number of items in the list
fruits[-1] accesses the last item in the list

Common Mistakes

Forgetting that indexing starts at 0, not 1
Trying to access an index that doesn't exist (IndexError)

Key concepts

List creationZero-based indexingappend() and remove()Looping through lists

Important terms

List: An ordered, changeable collection of items in Python
Index: The numeric position of an item in a list, starting at 0

Worked examples

Problem

Access the second item in the list [10, 20, 30]

1. Index 1 refers to the second item
2. numbers[1]

Answer: 20

Quick revision

Lists store multiple values in order
Indexing starts at 0
append() adds items, remove() deletes them
len() gives the number of items
for loops iterate through list items

Check your understanding

Question 1 · Multiple choice

What index refers to the first item in a Python list?

Question 2 · Multiple choice

Which method adds an item to the end of a list?

Question 3 · True or false

Lists in Python can contain items of different data types.

Question 4 · Short answer

What does len([1,2,3]) return?

Question 5 · Short answer

How would you access the last item of a list called data?

Done with Lists & Arrays?

Functions Intro to Python