SOLVED Ratio-based chance?

[Energy Engine]

Hello GMC,

Just a quick one. Not sure if I'm missing something here, but is it possible to base chance outcome using a ratio? I have the following variables and logic:

strength = 3
resist = 7

ratio = strength/resist

and this would indicate about a 43% chance (3/7) for "A" happening, and about 57% (1 - (3/7) ) for "B" happening. But what would be the appropriate way to put this in code form?:

I have:

if (ratio)
{show_message("A")}
else
{show_message("B")}

but obviously something is missing so it doesn't work.

Any help appreciated. Thanks.

 

[Aajowa]

Not sure if this is the 'correct' way, but you might be able to set up the chance via;

r_strength = irandom_range(0,3) //3 being whatever variable you're using to determine strength
r_resistance = irandom_range(0,7) //7 being determined the same way

if (r_strength>=r_resistance){
//bleep bloop
}else{
//Neep norb
}

 

[Roldy]

Hello GMC,

Just a quick one. Not sure if I'm missing something here, but is it possible to base chance outcome using a ratio? I have the following variables and logic:

strength = 3
resist = 7

ratio = strength/resist

and this would indicate about a 43% chance (3/7) for "A" happening, and about 57% (1 - (3/7) ) for "B" happening. But what would be the appropriate way to put this in code form?:

I have:

if (ratio)
{show_message("A")}
else
{show_message("B")}

but obviously something is missing so it doesn't work.

Any help appreciated. Thanks.

There would be many ways to do this.

One way would to be to think about pies. e.g. you can think of 3/7ths as a pie cut into seven equal parts and you have 3 of those parts.

If you generated a random number using irandom_range, from 1 part to 7 parts, you could do "A" when the number is 1, 2, or 3 and "B" when the number is 4,5,6,7.

So something like:

strength = 3;
resist = 7;

// Choose a number between 1 and the value of 'resist' (currently 7)
var _value = irandom_range(1, resist);

if (_value <= strength) {
    show_debug_message("A");
} else {
    show_debug_message("B");
}

 

[AceKiron]

YellowAfterLife made a blog post about exactly this: https://yal.cc/gamemaker-weighted-choose/
Here's the script given for GMS 2.3+:

function choose_weighted() {
    var n = 0;
    for (var i = 1; i < argument_count; i += 2) {
        if (argument[i] <= 0) continue;
        n += argument[i];
    }
    
    n = random(n);
    for (var i = 1; i < argument_count; i += 2) {
        if (argument[i] <= 0) continue;
        n -= argument[i];
        if (n < 0) return argument[i - 1];
    }
    
    return argument[0];
}

 

[chamaeleon]

Under the assumption if strength is greater than or equal to resist it will always be successful, using your formula

if ( (strength/resist) >= random(1) ) {
    show_message("A");
} else {
    show_message("B");
}

I would hazard a guess there's no limit to number of ways one can solve it as all posts so far indicate.

 

[Energy Engine]

Thank you all for your input. Lots of solutions here to choose from, so the issue is definitely solved lol.