[arthurdead]

i needed a way the get a random idx from a array based on weights and i found this blog post by some random dude:
https://blog.bruce-hill.com/a-faster...-random-choice
and ported the alias method to sourcepawn

include:
https://github.com/arthurdead/sm-plu...liasrandom.inc

seems to work good enough for me:

#include <sourcemod>
#include <aliasrandom>

public void OnPluginStart()
{
	ArrayList randomnames = new ArrayList(ByteCountToCells(64));
	randomnames.PushString("test0");
	randomnames.PushString("test1");
	randomnames.PushString("test3");
	randomnames.PushString("test4");
	randomnames.PushString("test5");

	int len = randomnames.Length;
	ArrayList weights = new ArrayList(1, len);
	weights.Set(0, 15.0);
	weights.Set(1, 2.0);
	weights.Set(2, 70.5);
	weights.Set(3, 40.0);
	weights.Set(4, 5.0);

	AliasRandom test = new AliasRandom(weights);

	int attempts = 500;

	len = randomnames.Length;
	ArrayList nums = new ArrayList(1, len);
	for(int i = 0; i < len; ++i) {
		nums.Set(i, 0);
	}

	int fail = 0;

	char name[64];
	if(test != null) {
		for(int i = 0; i < attempts; ++i) {
			int idx = test.Get();
			if(idx == -1) {
				++fail;
				continue;
			}

			int num = nums.Get(idx);
			++num;
			nums.Set(idx, num);
		}
	}

	PrintToServer("ran %i times %i failed:", attempts, fail);

	for(int i = 0; i < len; ++i) {
		int num = nums.Get(i);
		randomnames.GetString(i, name, sizeof(name));
		float weight = weights.Get(i);
		PrintToServer("  got %s %i times (weight was %.1f)", name, num, weight);
	}

	delete nums;
	delete test;
	delete weights;
}

[eyal282]

Duck duck go my store jackpot plugin. I think mine is more efficient, and I doubt arraylists are necessary.

[Lux]

Originally Posted by eyal282 Duck duck go my store jackpot plugin. I think mine is more efficient, and I doubt arraylists are necessary.

-Post link to whatever code you are talking about.
-Perf test it whatever you are talking about and show results.
-Why not contribute with the more efficient code so everyone benefits using this include.


EDIT:I'v never used a weighting system tbh the blog was interesting, thanks for the include i will use it

[Desktop]

Originally Posted by eyal282 Duck duck go my store jackpot plugin. I think mine is more efficient, and I doubt arraylists are necessary.

Yeah, if you could submit the code, it would be really nice, since these funcs are not often seen here and they're very useful

[eyal282]

Originally Posted by Desktop Yeah, if you could submit the code, it would be really nice, since these funcs are not often seen here and they're very useful

https://github.com/eyal282/Alliedmod...ore-jackpot.sp

[Localia]

I got an error at 'target.Push(i)' .
I guess in extreme cases, the result of "GetRandomFloat (-1.0,1.0) " can be 0.0, so the 'ArrayList target' will remain as "null",which can cause error when "target.Push(i)"

	ArrayList smalls = new ArrayList(2);
	ArrayList bigs = new ArrayList(2);

	int small_i = 0;
	int big_i = 0;

	for(int i = 0; i < len; ++i) {
		float weight = weights.Get(i);

		if(weight == avg) 
		{
			weight += GetRandomFloat(-1.0, 1.0);
		}

		bool is_small = (weight < avg);
		bool is_big = (weight > avg);

		ArrayList target = null;
		int target_i = -1;
		if(is_small) 
		{
			target = smalls;
			target_i = small_i;
		} 
		else if(is_big) 
		{
			target = bigs;
			target_i = big_i;
		}

		target.Push(i);
		if(weight > 0.0 && avg > 0.0) {
			weight = weight/avg;
		} else {
			weight = 0.0;
		}
		target.Set(target_i, weight, 1);

		if(is_small) {
			++small_i;
		} else if(is_big) {
			++big_i;
		}
	}

I made a simple fix.

	if(weight == avg) 
	{
		weight += GetRandomInt(0,99) < 50? 0.00001:-0.00001;
	}