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57 lines
2.0 KiB
Plaintext
57 lines
2.0 KiB
Plaintext
scriptName "Functions\arrays\fn_selectRandomWeighted.sqf";
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/*
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File: fn_selectRandomWeighted.sqf
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Author: Joris-Jan van 't Land
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Description:
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Function to select a random item from an array, taking into account item weights.
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The weights should be Numbers between 0 and 1, with a maximum precision of hundreds.
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Parameter(s):
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_this select 0: source Array (Array of Any Value)
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_this select 1: weights (Array of Number)
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Returns:
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Any Value selected item
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TODO:
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[*] Algorithm is inefficient?
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*/
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private ["_array","_weights","_index","_weighted"];
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_array = _this select 0;
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_weights = _this select 1;
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//Parameter validation.
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if ((typeName _array) != (typeName [])) exitWith {debugLog "Log: [selectRandomWeighted] Array (0) must be an Array!"; nil};
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if ((typeName _weights) != (typeName [])) exitWith {debugLog "Log: [selectRandomWeighted] Weights (1) must be an Array!"; nil};
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if ((count _array) > (count _weights)) exitWith {debugLog "Log: [selectRandomWeighted] There must be at least as many elements in Weights (1) as there are in Array (0)!"; nil};
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//Created weighted array of indices.
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_weighted = [];
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for "_i" from 0 to ((count _weights) - 1) do
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{
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private ["_weight"];
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_weight = _weights select _i;
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//Ensure the weight is a Number.
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//If it's not, set weight to 0 to exclude it.
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if ((typeName _weight) != (typeName 0)) then {debugLog "Log: [selectRandomWeighted] Weights should be Numbers; weight set to 0!"; _weight = 0};
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//The weight should be a Number between 0 and 1.
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if (_weight < 0) then {debugLog "Log: [selectRandomWeighted] Weights should be more than or equal to 0; weight set to 0!"; _weight = 0};
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//if (_weight > 1) then {debugLog "Log: [selectRandomWeighted] Weights should be less than or equal to 1; weight set to 1!"; _weight = 1};
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//Normalize the weight for a precision of hundreds.
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_weight = round(_weight * 100);
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for "_k" from 0 to (_weight - 1) do
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{
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_weighted set [(count _weighted), _i];
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};
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};
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//Randomly select an index from the weighted array and therefore an element.
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_index = _weighted call BIS_fnc_selectRandom;
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_array select _index |