C#•17mo ago

Strange result calculating probability of hit

I'm getting a strange result when running this function

        int DamageHitBellCurveCalc() {
            var randomValue = Random.value;
            var finalValue = 0;
            if (randomValue > 0.8623f) {
                finalValue = 0;
            } else if (randomValue > 0.7424f) {
                finalValue = 1;
            } else if (randomValue > 0.6379f) {
                finalValue = 2;
            } else if (randomValue > 0.5469f) {
                finalValue = 3;
            } else if (randomValue > 0.4676f) {
                finalValue = 4;
            } else if (randomValue > 0.3986f) {
                finalValue = 5;
            } else if (randomValue > 0.3384f) {
                finalValue = 6;
            } else if (randomValue > 0.2860f) {
                finalValue = 7;
            } else if (randomValue > 0.2404f) {
                finalValue = 8;
            } else if (randomValue > 0.2006f) {
                finalValue = 9;
            } else if (randomValue > 0.1660f) {
                finalValue = 10;
            } else if (randomValue > 0.1358f) {
                finalValue = 11;
            } else if (randomValue > 0.0867f) {
                finalValue = 12;
            } else if (randomValue > 0.0667f) {
                finalValue = 13;
            } else if (randomValue > 0.0493f) {
                finalValue = 14;
            } else if (randomValue > 0.0342f) {
                finalValue = 15;
            } else if (randomValue > 0.0210f) {
                finalValue = 16;
            } else if (randomValue > 0.0096f) {
                finalValue = 17;
            } else if (randomValue > 0.0045f) {
                finalValue = 18;
            } else if (randomValue > 0.0023f) {
                finalValue = 19;
            } else if (randomValue > 0.0012f) {
                finalValue = 20;
            }
            return finalValue;
        }

        int DamageHitBellCurveCalc() {
            var randomValue = Random.value;
            var finalValue = 0;
            if (randomValue > 0.8623f) {
                finalValue = 0;
            } else if (randomValue > 0.7424f) {
                finalValue = 1;
            } else if (randomValue > 0.6379f) {
                finalValue = 2;
            } else if (randomValue > 0.5469f) {
                finalValue = 3;
            } else if (randomValue > 0.4676f) {
                finalValue = 4;
            } else if (randomValue > 0.3986f) {
                finalValue = 5;
            } else if (randomValue > 0.3384f) {
                finalValue = 6;
            } else if (randomValue > 0.2860f) {
                finalValue = 7;
            } else if (randomValue > 0.2404f) {
                finalValue = 8;
            } else if (randomValue > 0.2006f) {
                finalValue = 9;
            } else if (randomValue > 0.1660f) {
                finalValue = 10;
            } else if (randomValue > 0.1358f) {
                finalValue = 11;
            } else if (randomValue > 0.0867f) {
                finalValue = 12;
            } else if (randomValue > 0.0667f) {
                finalValue = 13;
            } else if (randomValue > 0.0493f) {
                finalValue = 14;
            } else if (randomValue > 0.0342f) {
                finalValue = 15;
            } else if (randomValue > 0.0210f) {
                finalValue = 16;
            } else if (randomValue > 0.0096f) {
                finalValue = 17;
            } else if (randomValue > 0.0045f) {
                finalValue = 18;
            } else if (randomValue > 0.0023f) {
                finalValue = 19;
            } else if (randomValue > 0.0012f) {
                finalValue = 20;
            }
            return finalValue;
        }

21 Replies

Birdman•17mo ago

at finalValue = 12; there is a strangely large number of probabilities being created this is how i'm printing the results

            var array = new int[21];
            
            
            for (int i = 0; i < 100000; i++) {
                array[DamageHitBellCurveCalc()]++;
            }
            
            
            for (int i = 0; i < array.Length; i++) {
                print("NUMBER " + i + ": " + array[i]);
            }

            var array = new int[21];
            
            
            for (int i = 0; i < 100000; i++) {
                array[DamageHitBellCurveCalc()]++;
            }
            
            
            for (int i = 0; i < array.Length; i++) {
                print("NUMBER " + i + ": " + array[i]);
            }

i'm not sure why, maybe it's because the float starts with 0.0 or something?

Angius•17mo ago

Why do a Yandev-like wall of if-elses rather than using math?

Birdman•17mo ago

cause honestly i have no clue how to make a formula to calculate that

ACiDCA7•17mo ago

where does random.value come from? will it update with every call? isnt the correct way to get a random number .Next() or so

Birdman•17mo ago

comes from the unity game engine, yes it gives a random value every call

ACiDCA7•17mo ago

ah ok

Birdman•17mo ago

hmm, could it be a flaw with the random function itself 🤔

Angius•17mo ago

It's Unity, so it's entirely possible ¯\_(ツ)_/¯

Birdman•17mo ago

but technically there is nothing wrong with this code right? it should print out a proper bell curb of values?

Angius•17mo ago

I mean, the float values are pure magic So hard to tell at a glance what it'll do

Birdman•17mo ago

oh, nvm, got it the difference bewteen 0.1358f and 0.0867f is too large so naturally is assigns more values there, as it should okay, fixed 👍

Angius•17mo ago

1 occured 1208 times
0 occured 1397 times
2 occured 997 times
3 occured 960 times
14 occured 191 times
10 occured 370 times
7 occured 510 times
5 occured 678 times
9 occured 389 times
12 occured 460 times
15 occured 143 times
6 occured 588 times
11 occured 292 times
18 occured 45 times
13 occured 217 times
4 occured 836 times
8 occured 449 times
17 occured 106 times
16 occured 130 times
19 occured 28 times
20 occured 6 times

1 occured 1208 times
0 occured 1397 times
2 occured 997 times
3 occured 960 times
14 occured 191 times
10 occured 370 times
7 occured 510 times
5 occured 678 times
9 occured 389 times
12 occured 460 times
15 occured 143 times
6 occured 588 times
11 occured 292 times
18 occured 45 times
13 occured 217 times
4 occured 836 times
8 occured 449 times
17 occured 106 times
16 occured 130 times
19 occured 28 times
20 occured 6 times

var nums = new List<int>();

for (var i = 0; i < 10_000; i++)
{
    nums.Add(BellCurve());
}

foreach (var vals in nums.GroupBy(x => x).Select(x => $"{x.Key} occured {x.Count()} times"))
{
    Console.WriteLine(vals);
}

static int BellCurve() =>
    Random.Shared.NextSingle() switch
    {
        > 0.8623f => 0,
        > 0.7424f => 1,
        > 0.6379f => 2,
        > 0.5469f => 3,
        > 0.4676f => 4,
        > 0.3986f => 5,
        > 0.3384f => 6,
        > 0.2860f => 7,
        > 0.2404f => 8,
        > 0.2006f => 9,
        > 0.1660f => 10,
        > 0.1358f => 11,
        > 0.0867f => 12,
        > 0.0667f => 13,
        > 0.0493f => 14,
        > 0.0342f => 15,
        > 0.0210f => 16,
        > 0.0096f => 17,
        > 0.0045f => 18,
        > 0.0023f => 19,
        > 0.0012f => 20,
        _ => 0
    };

var nums = new List<int>();

for (var i = 0; i < 10_000; i++)
{
    nums.Add(BellCurve());
}

foreach (var vals in nums.GroupBy(x => x).Select(x => $"{x.Key} occured {x.Count()} times"))
{
    Console.WriteLine(vals);
}

static int BellCurve() =>
    Random.Shared.NextSingle() switch
    {
        > 0.8623f => 0,
        > 0.7424f => 1,
        > 0.6379f => 2,
        > 0.5469f => 3,
        > 0.4676f => 4,
        > 0.3986f => 5,
        > 0.3384f => 6,
        > 0.2860f => 7,
        > 0.2404f => 8,
        > 0.2006f => 9,
        > 0.1660f => 10,
        > 0.1358f => 11,
        > 0.0867f => 12,
        > 0.0667f => 13,
        > 0.0493f => 14,
        > 0.0342f => 15,
        > 0.0210f => 16,
        > 0.0096f => 17,
        > 0.0045f => 18,
        > 0.0023f => 19,
        > 0.0012f => 20,
        _ => 0
    };

And here I wrote a nice test app lol

Birdman•17mo ago

that's strange, why are the values in the random order, makes it hard to see discrepancies

Angius•17mo ago

Well, the values generated were random So the GroupBy() took the first value of the kind, and grouped the rest to it I can sort it, no problem And let's crank up the numbers to 100k

0 occured 13789 times
1 occured 12043 times
2 occured 10438 times
3 occured 9145 times
4 occured 7821 times
5 occured 7005 times
6 occured 6032 times
7 occured 5371 times
8 occured 4617 times
9 occured 4031 times
10 occured 3461 times
11 occured 2939 times
12 occured 4818 times
13 occured 1985 times
14 occured 1692 times
15 occured 1503 times
16 occured 1293 times
17 occured 1131 times
18 occured 541 times
19 occured 236 times
20 occured 109 times

0 occured 13789 times
1 occured 12043 times
2 occured 10438 times
3 occured 9145 times
4 occured 7821 times
5 occured 7005 times
6 occured 6032 times
7 occured 5371 times
8 occured 4617 times
9 occured 4031 times
10 occured 3461 times
11 occured 2939 times
12 occured 4818 times
13 occured 1985 times
14 occured 1692 times
15 occured 1503 times
16 occured 1293 times
17 occured 1131 times
18 occured 541 times
19 occured 236 times
20 occured 109 times

Birdman•17mo ago

yup, same result there's a missing value this 0.1095f then it works properly i missed it when i was copying from my excel lol

Angius•17mo ago

Where should it be?

Birdman•17mo ago

after the next biggest one after this > 0.1358f => 11, and then reorder the numbers that are output

Angius•17mo ago

Birdman•17mo ago

yup 👍

Angius•17mo ago

0 occured 13989 times
1 occured 12126 times
2 occured 10387 times
3 occured 9046 times
4 occured 7934 times
5 occured 6939 times
6 occured 6015 times
7 occured 5293 times
8 occured 4510 times
9 occured 3991 times
10 occured 3418 times
11 occured 3033 times
12 occured 2557 times
13 occured 2246 times
14 occured 1918 times
15 occured 1699 times
16 occured 1507 times
17 occured 1308 times
18 occured 1171 times
19 occured 544 times
20 occured 247 times
21 occured 122 times

0 occured 13989 times
1 occured 12126 times
2 occured 10387 times
3 occured 9046 times
4 occured 7934 times
5 occured 6939 times
6 occured 6015 times
7 occured 5293 times
8 occured 4510 times
9 occured 3991 times
10 occured 3418 times
11 occured 3033 times
12 occured 2557 times
13 occured 2246 times
14 occured 1918 times
15 occured 1699 times
16 occured 1507 times
17 occured 1308 times
18 occured 1171 times
19 occured 544 times
20 occured 247 times
21 occured 122 times

Birdman•17mo ago

👍

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Strange result calculating probability of hit