1D Arrays (Lists)
Learn how to store multiple values in a single variable using arrays (called lists in Python).
What you'll learn:
- What arrays are and why we use them
- Creating and accessing array elements by index
- Modifying array elements
- Using loops to iterate through arrays
- Common array operations: length, append, remove
Learning Path
Follow these activities in order.
1. Predict: What's in the Array?
Predict what array operations will output.
2. Study: Worked Example
See how to create and manipulate arrays step by step.
3. Investigate: Trace Array Operations
Track how array contents change through loops.
4. Modify: Arrange the Code
Put code blocks in order to work with arrays.
5. Test: Knowledge Quiz
Check your understanding of 1D arrays.
Key Vocabulary
array / list
A data structure that stores multiple values in a single variable. In Python, we use lists.
element
A single item stored in an array. ["a", "b", "c"] has 3 elements.
index
The position of an element. Starts at 0! First element is at index 0.
length
The number of elements in an array. Use len(array) to find it.
append
Add an element to the end of an array. array.append(value)
iteration
Going through each element of an array one by one, usually with a loop.
Quick Reference
# Creating an array (list)
scores = [85, 92, 78, 90, 88]
names = ["Alice", "Bob", "Charlie"]
empty = []
# Accessing elements by index (starts at 0!)
print(scores[0]) # First element: 85
print(scores[2]) # Third element: 78
print(scores[-1]) # Last element: 88
# Modifying elements
scores[0] = 95 # Change first element to 95
# Array length
print(len(scores)) # 5
# Adding and removing elements
scores.append(100) # Add 100 to the end
scores.remove(78) # Remove first occurrence of 78
# Looping through an array - by element
for score in scores:
print(score)
# Looping through an array - by index
for i in range(len(scores)):
print("Index", i, "=", scores[i])