Difference between revisions of "random"

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m (Text replacement - " \|([ps][0-9]+) *= " to " |$1= ")
m (Text replacement - "[[Image:" to "[[File:")
 
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|gr1= Math
 
|gr1= Math
  
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|descr= [[Image:bellcurve.jpg|right|200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br><br>
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|descr= [[File:bellcurve.jpg|thumb|120px|[[#Syntax 2|Syntax&nbsp;2]]'s distribution]]
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{{GVI|arma3|1.56}} alternative syntax is added, allowing the definition of {{Wikipedia|Normal_distribution|Gaussian Distribution}}<ref>Technically, it is a rescaled {{Wikipedia|Bates_distribution|Bates distribution}} with n = 4. The distribution is split in two at its midpoint and scaled linearly such that its maximum lies at the specified midpoint.</ref> params. Uses the same method as [[setTriggerTimeout]] command. Quite useful for spawning loot for example, making more valuable items more rare ({{HashLink|#Alternative Syntax 1}})<br><br>
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{{{!}}
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{{GVI|arma3|1.68}} two alternative syntaxes are available:
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! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}} {{Link|#Syntax 1}}
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* allowing to generate {{Wikipedia|Random seed|seed-based}} random number based on provided seed ({{HashLink|#Alternative Syntax 2}})
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{{!}} generates a random floating point value
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* generating {{Wikipedia|Random seed|seed-based}} random noise texture based on provided seed and returning a single number between 0 (included) and 1 (excluded) at supplied ''x'' and ''y'' coordinates ({{HashLink|#Alternative Syntax 3}})
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{{!}}-
 +
! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}}  {{Link|#Syntax 2}}
 +
{{!}} generates a {{Link|https://en.wikipedia.org/wiki/Normal_distribution|Gaussian Distribution}}<ref>Technically, it is a rescaled {{Link|https://en.wikipedia.org/wiki/Bates_distribution}} with n = 4. The distribution is split in two at its midpoint and scaled linearly such that its maximum lies at the specified midpoint.</ref>. It uses the same method as [[setTriggerTimeout]] command and is quite useful for e.g spawning loot, making more valuable items more rare
 +
{{!}}-
 +
! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}}  {{Link|#Syntax 3}}
 +
{{!}} generates a {{Link|https://en.wikipedia.org/wiki/Random_seed|seed-based}} random number
 +
{{!}}-
 +
! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}}  {{Link|#Syntax 4}}
 +
{{!}} generates a {{Link|https://en.wikipedia.org/wiki/Random_seed|seed-based}} random noise ('''not''' Perlin) texture based on provided seed and returning the value at supplied coordinates
 +
{{!}}}
  
 
|s1= [[random]] x
 
|s1= [[random]] x
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|p1= x: [[Number]]
 
|p1= x: [[Number]]
  
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|r1= [[Number]]
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|r1= [[Number]] from 0 (included) to ''x'' (excluded)
  
 
|s2= [[random]] [min, mid, max]
 
|s2= [[random]] [min, mid, max]
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|s2since= arma3 1.56
 
|s2since= arma3 1.56
  
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|p21= [min, mid, max]: [[Array]]
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|p21= min: [[Number]]
  
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|p22= min: [[Number]]
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|p22= mid: [[Number]]
  
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|p23= mid: [[Number]]
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|p23= max: [[Number]]
  
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|p24= max: [[Number]]
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|r2= [[Number]] in range from ''min'' to ''max'', weighted by ''mid''
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|r2= [[Number]]
 
  
 
|s3= seed [[random]] x
 
|s3= seed [[random]] x
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|p42= x: [[Number]]
 
|p42= x: [[Number]]
  
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|r3= [[Number]] - Value from 0 to x
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|r3= [[Number]] from 0 (included) to ''x'' (excluded)
  
 
|s4= seed [[random]] [x, y]
 
|s4= seed [[random]] [x, y]
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|p61= seed: [[Number]]
 
|p61= seed: [[Number]]
  
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|p62= [x, y]: [[Array]] - texture position (''not'' a Perlin noise)
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|p62= x: [[Number]] - x texture position
 +
 
 +
|p63= y: [[Number]] - y texture position
 +
 
 +
|r4= [[Number]] from 0 (included) to 1 (excluded)
 +
 
 +
|x1= <sqf>_rNumber = random 1;</sqf>
  
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|p63= x: [[Number]]
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|x2= <sqf>_rNumber = random -10;</sqf>
  
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|p64= y: [[Number]]
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|x3= Generate a random position inside a circle (see also [[Example Code: Random Area Distribution]])
 +
<sqf>_center getPos [_radius * sqrt random 1, random 360];</sqf>
  
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|r4= [[Number]] - Value from 0 to 1
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|x4= Select a random value from an array:
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<sqf>
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_array = ["apples", "pears", "bananas", "M16"];
  
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|x1= <code>_rNumber = [[random]] 1;</code>
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_random = _array select floor random count _array; // before {{arma2}}
 +
_random = _array call BIS_fnc_selectRandom; // since {{arma2}}
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_random = selectRandom _array; // since {{arma3}} v1.56
 +
</sqf>
  
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|x2= <code>_rNumber = [[random]] -10;</code>
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|x5= Visualization of Syntax 4 (warning, it takes a bit to execute to draw):
 +
<sqf>
 +
private _parent = call BIS_fnc_displayMission;
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if (is3DEN) then { _parent = findDisplay 313 };
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private _disp = _parent createDisplay "RscDisplayEmpty";
 +
private _BG = _disp ctrlCreate ["RscBackground", -1];
  
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|x3= Generate a random position inside a circle (see also [[Example Code: Random Area Distribution]])
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private _coef = 0.1;
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<code>_center [[getPos]] [_radius * [[sqrt]] [[random]] 1, [[random]] 360];</code>
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 +
for "_x" from 1 to 100 do
 +
{
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for "_y" from 1 to 100 do
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{
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private _random = 0 random [_x * _coef, _y * _coef];
 +
private _dot = _disp ctrlCreate ["RscBackground", -1];
  
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|x4= To select random value from an array:
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_dot ctrlSetPosition [0.5 + pixelW * _x, 0.5 + pixelH * _y, pixelW, pixelH];
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<code>_array = ["apples", "pears", "bananas", "M16"];
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_dot ctrlSetBackgroundColor [_random, _random, _random, 1];
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_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
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_dot ctrlCommit 0;
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{{cc|{{Since|arma3|1.56}}}}
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};
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_random = [[selectRandom]] _array;</code>
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};
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</sqf>
 +
[[File:A3 random syntax4.png|thumb|left|Example result]]
  
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|seealso= [[selectRandom]], [[selectRandomWeighted]]
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|seealso= [[selectRandom]] [[selectRandomWeighted]] [[Example Code: Random Area Distribution]]
 
}}
 
}}
  
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<dl class="command_description">
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{{Note
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|user= Hcpookie
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<dt></dt>
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|timestamp= 20150712203200
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<dd class="notedate">Posted on July 12, 2015 - 20:32 (UTC)</dd>
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|text= Random selections including negative numbers can be obtained via:
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<dt class="note">[[User:Hcpookie|Hcpookie]]</dt>
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<sqf>_xRnd = round (random 200) - 100;</sqf>
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<dd class="note">
 
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Random selections including negative numbers can be obtained via:
 
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<code>_Xrnd = round(random 200) -100;</code>
 
  
 
This will yield numbers between -100 and 100.
 
This will yield numbers between -100 and 100.
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* The number returned is unlikely to be a whole number.<br>
 
* The number returned is unlikely to be a whole number.<br>
 
To return a whole number use either '''[[round]]''', '''[[ceil]]''' or '''[[floor]]''' together with [[random]]:
 
To return a whole number use either '''[[round]]''', '''[[ceil]]''' or '''[[floor]]''' together with [[random]]:
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<code>x = [[round]] ([[random]] 5) will return 0, 1, 2, 3, 4 or 5. (non-uniform distribution, 0 and 5 are half as likely to be selected than any of the other numbers)
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<sqf>
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x = [[floor]] ([[random]] 5) will return 0, 1, 2, 3 or 4.   (uniform distribution, all numbers have the same probability of being selected)
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x = round (random 5) // will return 0, 1, 2, 3, 4 or 5. (non-uniform distribution, 0 and 5 are half as likely to be selected than any of the other numbers)
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x = [[ceil]] ([[random]] 5) will return 0, 1, 2, 3, 4 or 5. (0 is very unlikely, but possible, as ceil 0 is 0)</code>
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x = floor (random 5) // will return 0, 1, 2, 3 or 4.   (uniform distribution, all numbers have the same probability of being selected)
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</dd>
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x = ceil  (random 5) // will return 0, 1, 2, 3, 4 or 5. (0 is very unlikely, but possible, as ceil 0 is 0)
 +
</sqf>
 +
}}
  
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<dd class="notedate">Posted on July 22, 2018 - 12:58 (UTC+2)</dd>
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{{Note
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<dt class="note">[[User:Lou Montana|Lou Montana]]</dt>
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|user= Lou Montana
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<dd class="note">
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|timestamp= 20180722125800
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{| class="wikitable"
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|text= <nowiki/>
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|+ Repartition comparison
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{{{!}} class="wikitable align-right align-left-col-1 align-center-row-1"
 +
{{!}}+ Repartition comparison
 
! Formula
 
! Formula
 
! 0
 
! 0
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! 8
 
! 8
 
! 9
 
! 9
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|-
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{{!}}-
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| [[floor]] [[random]] 10;
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{{!}} <sqf>floor random 10</sqf>
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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| 10%
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{{!}} 10%
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|-
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{{!}}-
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| [[floor]] [[random]] [0, 5, 10]
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{{!}} <sqf>floor random [0, 5, 10]</sqf>
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| 0%
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{{!}} 0%
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| 2%
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{{!}} 2%
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| 7%
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{{!}} 7%
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| 17%
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{{!}} 17%
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| 25%
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{{!}} 25%
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| 25%
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{{!}} 25%
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| 17%
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{{!}} 17%
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| 7%
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{{!}} 7%
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| 2%
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{{!}} 2%
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| 0%
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{{!}} 0%
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|-
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{{!}}-
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| [[floor]] [[random]] [0, 10, 0]
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{{!}} <sqf>floor random [0, 10, 0]</sqf>
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| 0%
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{{!}} 0%
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| 0%
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{{!}} 0%
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| 1%
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{{!}} 1%
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| 2%
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{{!}} 2%
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| 5%
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{{!}} 5%
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| 9%
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{{!}} 9%
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| 14%
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{{!}} 14%
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| 19%
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{{!}} 19%
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| 24%
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{{!}} 24%
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| 26%
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{{!}} 26%
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|-
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{{!}}-
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| [[floor]] [[random]] [0, 10, 5]
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{{!}} <sqf>floor random [0, 10, 5]</sqf>
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| 0%
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{{!}} 0%
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| 0%
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{{!}} 0%
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| 0%
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{{!}} 0%
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| 1%
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{{!}} 1%
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| 2%
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{{!}} 2%
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| 5%
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{{!}} 5%
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| 9%
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{{!}} 9%
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| 16%
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{{!}} 16%
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| 28%
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{{!}} 28%
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| 38%
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{{!}} 38%
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|}
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{{!}}}
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</dd>
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}}
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</dl>
 

Latest revision as of 23:12, 20 November 2023

Logo A0.png1.00ofpe logo.png1.00Logo A1 black.png1.00Logo A2.png1.00A2 OA Logo.png1.50tkoh logo small.png1.00Arma 3 logo black.png0.50
Hover & click on the images for description

Description

Description:
Syntax 2's distribution
Syntax 1 generates a random floating point value
Syntax 2 generates a Gaussian Distribution[1]. It uses the same method as setTriggerTimeout command and is quite useful for e.g spawning loot, making more valuable items more rare
Syntax 3 generates a seed-based random number
Syntax 4 generates a seed-based random noise (not Perlin) texture based on provided seed and returning the value at supplied coordinates
Groups:
Math

Syntax 1

Syntax:
random x
Parameters:
x: Number
Return Value:
Number from 0 (included) to x (excluded)

Syntax 2

Syntax:
random [min, mid, max]
Parameters:
min: Number
mid: Number
max: Number
Return Value:
Number in range from min to max, weighted by mid

Syntax 3

Syntax:
seed random x
Parameters:
seed: Number - an integer. Any float value will be truncated (e.g -0.9, -0.1, 0.1 or 0.9 will be read as 0)
x: Number
Return Value:
Number from 0 (included) to x (excluded)

Syntax 4

Syntax:
seed random [x, y]
Parameters:
seed: Number
x: Number - x texture position
y: Number - y texture position
Return Value:
Number from 0 (included) to 1 (excluded)

Examples

Example 1:
_rNumber = random 1;
Example 2:
_rNumber = random -10;
Example 3:
Generate a random position inside a circle (see also Example Code: Random Area Distribution)
_center getPos [_radius * sqrt random 1, random 360];
Example 4:
Select a random value from an array:
_array = ["apples", "pears", "bananas", "M16"]; _random = _array select floor random count _array; // before Arma 2 _random = _array call BIS_fnc_selectRandom; // since Arma 2 _random = selectRandom _array; // since Arma 3 v1.56
Example 5:
Visualization of Syntax 4 (warning, it takes a bit to execute to draw):
private _parent = call BIS_fnc_displayMission; if (is3DEN) then { _parent = findDisplay 313 }; private _disp = _parent createDisplay "RscDisplayEmpty"; private _BG = _disp ctrlCreate ["RscBackground", -1]; private _coef = 0.1; for "_x" from 1 to 100 do { for "_y" from 1 to 100 do { private _random = 0 random [_x * _coef, _y * _coef]; private _dot = _disp ctrlCreate ["RscBackground", -1]; _dot ctrlSetPosition [0.5 + pixelW * _x, 0.5 + pixelH * _y, pixelW, pixelH]; _dot ctrlSetBackgroundColor [_random, _random, _random, 1]; _dot ctrlCommit 0; }; };
Example result

Additional Information

See also:
selectRandom selectRandomWeighted Example Code: Random Area Distribution

Notes

Report bugs on the Feedback Tracker and/or discuss them on the Arma Discord or on the Forums.
Only post proven facts here! Add Note
Hcpookie
Posted on Jul 12, 2015 - 20:32 (UTC)
Random selections including negative numbers can be obtained via:
_xRnd = round (random 200) - 100;
This will yield numbers between -100 and 100.
  • Be careful using random numbers in multiplayer, each client will come up with a different result. See multiplayer tutorials for more general information about locality.
  • The number returned is unlikely to be a whole number.
To return a whole number use either round, ceil or floor together with random:
x = round (random 5) // will return 0, 1, 2, 3, 4 or 5. (non-uniform distribution, 0 and 5 are half as likely to be selected than any of the other numbers) x = floor (random 5) // will return 0, 1, 2, 3 or 4. (uniform distribution, all numbers have the same probability of being selected) x = ceil (random 5) // will return 0, 1, 2, 3, 4 or 5. (0 is very unlikely, but possible, as ceil 0 is 0)
Lou Montana
Posted on Jul 22, 2018 - 12:58 (UTC)
Repartition comparison
Formula 0 1 2 3 4 5 6 7 8 9
floor random 10
 10% 10% 10% 10% 10% 10% 10% 10% 10% 10%
floor random [0, 5, 10]
 0% 2% 7% 17% 25% 25% 17% 7% 2% 0%
floor random [0, 10, 0]
 0% 0% 1% 2% 5% 9% 14% 19% 24% 26%
floor random [0, 10, 5]
 0% 0% 0% 1% 2% 5% 9% 16% 28% 38%
  1. ↑ Technically, it is a rescaled Bates distribution with n = 4. The distribution is split in two at its midpoint and scaled linearly such that its maximum lies at the specified midpoint.
Retrieved from "https://community.bistudio.com/wiki?title=random&oldid=350033"