Code Labs: Data Structures

Put Arrays, Indexing, and 2D Matrices into practice.

Interactive Engine

Use the interactive terminal below to test Python Lists (1D Arrays).

array_demo.py

# A 1D Array
names = ["Alan", "Ada", "Tim"]

# Accessing the second element
print("Element at Index 1:", names[1])

# Adding a new element (Python list append)
names.append("Grace")
print("Full Array:", names)

Console Output

> Waiting to compile...

The Crucible

Prove your knowledge of arrays and indexing.

Bronze (1D Indexing)

The Precise Extraction

You have an RPG inventory array: ["Sword", "Shield", "Potion", "Map"]. Remember that counting strictly starts at 0.

Task: Use square brackets [] to extract and print exactly the word "Potion".

bronze.py

inventory = ["Sword", "Shield", "Potion", "Map"]

# Print the 3rd item in the array
print(inventory[???])

> Output will appear here...

Silver (Modification)

Overwriting Data

Arrays are mutable (they can be changed). We need to fix a corrupted database score.

Task: Without deleting the array creation line, overwrite the very first score in the array so it equals 99 instead of 10.

silver.py

scores = [10, 50, 100, 250]

# Overwrite the first score (Index 0) to equal 99
scores[0] = ???

print(scores)

> Output will appear here...

Gold (2D Arrays)

The Database Matrix

A 2D Array is just an array inside another array. To access it, you need TWO indexes: database[Row][Column].

Task: Look at the 2D array below (it represents a database table of usernames and passwords). Use 2D indexing to print the username "Admin".

gold.py

# A 2D Array (List of Lists)
db = [
    ["User1", "Pass123"],  # Row 0
    ["Admin", "SuperSecretPW"],  # Row 1
    ["Guest", "P@ssword"]  # Row 2
]

# Print exactly the string "Admin":
print(db[???][???])

> Output will appear here...

Return to Theory Guide

Interactive Engine

User Input Required

The Precise Extraction

Overwriting Data

The Database Matrix