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Set variable to random choice between specific values

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GA

GameBuilder_Alex

Posted on July 23, 2025 • Beginner

🎲 Random choice between specific values

Hey everyone! I’m working on a fun little game and I need to set a variable to randomly choose between two specific values. Not a random number in a range, but literally pick one value OR another value.

For example, I want to set a variable to either 3 or -3 (nothing in between). I tried something like:

set [my variable v] to <<3> or <-3>>

But that doesn’t work the way I expected. How do I make it randomly pick one specific value or another? 🤔

RC

RandomCoder_Pro

Replied 2 hours later • ⭐ Best Answer

Great question @GameBuilder_Alex! The “or” block in Scratch is a boolean operator, not a choice selector. Let me show you several ways to randomly choose between specific values:

🎯 Random Choice Methods

Here’s how different random selection methods work:

flowchart TD A[🎲 Random Choice Methods] --> B[Method 1: If-Else] A --> C[Method 2: List Selection] A --> D[Method 3: Mathematical] A --> E[Method 4: Multiple Values] B --> F[Generate 1 or 2] F --> G[If 1: Value A] F --> H[If 2: Value B] C --> I[Create List] I --> J[Pick Random Item] D --> K[Use Math Formula] K --> L[Multiply & Subtract] E --> M[Repeat Until Match] style A fill:#e1f5fe style B fill:#e8f5e8 style C fill:#fff3e0 style D fill:#f3e5f5 style E fill:#fce4ec

🔧 Method 1: If-Else Approach (Recommended)

This is the most straightforward and readable method:

    if <(pick random (1) to (2)) = [1]> then
set [my variable v] to [3]
else
set [my variable v] to [-3]
end

How it works:

  • Generate a random number: 1 or 2
  • If it’s 1, set variable to first value (3)
  • If it’s 2, set variable to second value (-3)

📋 Method 2: List Selection

Great for multiple choices or when values change frequently:

    // Setup (do this once)
delete all of [choices v]
add [3] to [choices v]
add [-3] to [choices v]

// Random selection
set [my variable v] to (item (pick random (1) to (length of [choices v])) of [choices v])

Advantages:

  • Easy to add more choices
  • Can store any type of values (numbers, text)
  • Reusable for different variables

🧮 Method 3: Mathematical Approach

For your specific case (3 or -3), you can use math:

    // Method 3a: Simple multiplication
set [my variable v] to (((pick random (0) to (1)) * (2)) - (1))
set [my variable v] to ((my variable) * (3))

// Method 3b: Direct calculation
set [my variable v] to (((pick random (1) to (2)) * (2)) - (1))
set [my variable v] to ((my variable) * (3))

How Method 3a works:

  • Pick random 0 or 1
  • Multiply by 2: gives 0 or 2
  • Subtract 1: gives -1 or 1
  • Multiply by 3: gives -3 or 3

🔄 Method 4: Repeat Until (For Complex Conditions)

When you need specific conditions or multiple possible values:

    repeat until <<(my variable) = [3]> or <(my variable) = [-3]>>
set [my variable v] to (pick random (-5) to (5))
end

Or using absolute value for your specific case:

    repeat until <([abs v] of (my variable)) = [3]>
set [my variable v] to (pick random (-5) to (5))
end

🚀 Advanced: Weighted Random Selection

If you want some values to be more likely than others:

    // 70% chance of 3, 30% chance of -3
if <(pick random (1) to (10)) ≤ [7]> then
set [my variable v] to [3]
else
set [my variable v] to [-3]
end

💡 Best Practices

  • Use Method 1 for simple two-choice scenarios
  • Use Method 2 when you have many choices or they change
  • Use Method 3 for mathematical patterns
  • Use Method 4 for complex conditions

For your specific case (3 or -3), I’d recommend Method 1 - it’s clear, efficient, and easy to understand! 😊

GA

GameBuilder_Alex

Replied 30 minutes later

@RandomCoder_Pro This is exactly what I needed! Thank you so much! 🎉

I went with Method 1 and it works perfectly. I love how you explained all the different approaches - the list method looks really useful for when I need more than two choices.

Quick question: does the mathematical method (Method 3) run faster than the if-else method?

PT

PerformanceTuner_Sam

Replied 1 hour later

@GameBuilder_Alex Great question about performance! In Scratch, the difference is negligible for most projects. Here’s the breakdown:

  • Mathematical method: Slightly faster (fewer blocks to execute)
  • If-else method: More readable and maintainable
  • List method: Most flexible but slightly slower

Unless you’re doing this thousands of times per second, go with readability over micro-optimizations! 😊

GD

GameDesigner_Maya

Replied 2 hours later

Love this discussion! Here’s a real-world example of when I use each method:

  • If-else: Player direction (left/right), coin flip results
  • List method: Random enemy types, random sound effects, random colors
  • Mathematical: Symmetric values like yours (positive/negative)
  • Repeat until: Generating unique random positions

Each method has its perfect use case! 🎮

VB

Vibelf_Community

Pinned Message • Moderator

🚀 Want to Master Random Logic and Game Mechanics?

Fantastic discussion about random selection methods! For those looking to implement more advanced randomization and game logic, our community can help you with:

  • 🎲 Probability and weighted randomization
  • 🔄 Procedural generation techniques
  • 🎮 Advanced game mechanics
  • ⚡ Performance optimization strategies

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