C. The Variable i Basket

← B. The range() Number Factory ⏱️ 5 min D. Indentation →

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🎯 Learning Goals

By the end of this lesson, you'll be able to:

• ○ The variable iUnderstand its role
• ○ iUnderstand that it changes on every repetition
• ○ iBe able to use it in code

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Core Concepts

What is the variable i?

🧺 Analogy: a number basket

Variable iholds the current number, like a basketIt is!

Every time the carousel spins, a new number goes into the basket.

How i's value changes

for i in range(3):
    print(i)

Repeat	i's value
1st	0
2nd	1
3rd	2

Putting i to use

for i in range(3):
    print(f"This is the {i}!")

# Output:
# This is number 0!
# This is number 1!
# This is number 2!

Using it in a game

for i in range(5):
    Entity(
        model='cube',
        position=(i * 2, 0, 0)  # Calculate position with i!
    )

Result: 5 cubes are placed along the x-axis!

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Example Code

from ursina import *

app = Ursina()

# Calculate position using i
for i in range(5):
    Entity(
        model='cube',
        color=color.red,
        position=(i * 2, 0, 0)  # Positions 0, 2, 4, 6, 8
    )

EditorCamera()
app.run()

What Happens

5 cubes are placed at even intervals!

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Quiz

Quiz: Number of repetitions

for i in range(8)how many times does it repeat?

Check answers

Show Answer

Answer: 8

for i in range(8)repeats 8 times total, from 0 to 7. range(n)always repeats n times!

Variable i practice:

• The variable that holds the current number: for in range(5):
• Calculate i times 2: position = i *
• i's last value when range(4):

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🔧 Debug Clinic

Problem: every object is created at the same position

❌ Wrong Code

for i in range(5):
    Entity(model='cube', position=(0, 0, 0))  # All at (0,0,0)!

Cause: iwasn't used in the position calculation

✅ Correct Code

for i in range(5):
    Entity(model='cube', position=(i * 2, 0, 0))  # Positions 0, 2, 4, 6, 8

Fix: iUse it to calculate the position!

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Try Coding It Yourself

Take what you learned with the blocks and write it yourself in Python code!

Printing i's value

Check how the variable i changes on each repetition.

Example Answer

for i in range(5):
    print(f'Current i = {i}')

Result: i is printed as it changes from 0 to 4!

Using i in calculations

Use the variable i to calculate positions!

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🎯 Fill-in-the-Blank Mission

Fill in the blanks to complete the code!

Check answers

for i in range(4):
    print(f'Current number: {i}')

Check answers

for i in range(5):
    result = i * 3
    print(f'{i} x 3 = {result}')

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🧩 Key Takeaways

What you learned in this lesson:

Concept	Description
Variable i	a basket that holds the current loop number
How the value changes	A new number goes in on each repetition
How to use it	Used to calculate position, size, etc.

Review Checklist

• [ ] The variable ican you explain what it holds?
• [ ] iCan you use it to give objects different positions?
• [ ] for i in range(5)in iDo you know what values it takes?

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← B. The range() Number Factory ⏱️ 5 min D. Indentation →