Difference between revisions of "random"
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Lou Montana (talk  contribs) m (Text replacement  " <! (DIS)?CONTINUE Notes >" to "") 

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−  {{  +  {{RVtype=command 
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−   ofp  +   ofp 
−  1.00  +  1.00 
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−    +  gr1= Math 
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−  '''random''' x   +  [[Image:bellcurve.jpgright200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br> 
+  <br>  
+  Since Arma 3 v1.56 alternative syntax is added, allowing the definition of [https://en.wikipedia.org/wiki/Normal_distribution Gaussian Distribution]<ref>Technically, it is a rescaled [https://en.wikipedia.org/wiki/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 ('''Alternative Syntax 1''')<br><br>  
+  Since Arma 3 v1.68 two alternative syntaxes are available:  
+  * allowing to generate semirandom number based on provided seed ('''Alternative Syntax 2''')  
+  * generating pseudorandom [https://en.wikipedia.org/wiki/Perlin_noise noise texture] based on provided seed and returning a single number between 0 (included) and 1 (excluded) at supplied ''x'' and ''y'' coordinates ('''Alternative Syntax 3''')  
+  
+   [[random]] x  
p1= x: [[Number]]  p1= x: [[Number]]  
−   [[Number]]  +   [[Number]] 
−  s2=  +  s2= [[random]] [min, mid, max] {{Sincearma31.55.133393y}} 
+  p21= [min, mid, max]: [[Array]]  
+  p22= min: [[Number]]  
+  p23= mid: [[Number]]  
+  p24= max: [[Number]]  
+  r2= [[Number]]  
−    +  s3= seed [[random]] x {{Sincearma31.67.139663y}} 
−    +  p41= seed: [[Number]] 
−    +  p42= x: [[Number]] 
−    +  r3= [[Number]]  value from 0 to x 
−    +  s4= seed [[random]] [x, y] {{Sincearma31.67.139663y}} 
−  +  p61= seed: [[Number]]  
+  p62= [x, y]: [[Array]] position on the [https://en.wikipedia.org/wiki/Perlin_noise Perlin noise texture]  
+  p63= x: [[Number]]  
+  p64= y: [[Number]]  
+  r4= [[Number]]  value from 0 to 1  
−  x1= <code>_rNumber = [[random]] 1;</code>  +  x1= <code>_rNumber = [[random]] 1;</code> 
−  x2= <code>_rNumber = [[random]] 10;</code>  +  x2= <code>_rNumber = [[random]] 10;</code> 
−  x3= To select random value from an array:  +  x3= Generate a random position inside a circle (see also [[Example Code: Random Area Distribution]]) 
+  <code>_center [[getPos]] [<nowiki/>_radius * [[sqrt]] [[random]] 1, [[random]] 360];</code>  
+  
+  x4= To select random value from an array:  
<code>_array = ["apples", "pears", "bananas", "M16"];  <code>_array = ["apples", "pears", "bananas", "M16"];  
−  _random = _array [[select]] [[floor]] [[random]] [[count]] _array;  +  _random = _array [[select]] [[floor]] [[random]] [[count]] _array; 
−  +  {{cc{{Sincearma31.55.133393}}}}  
−    +  _random = [[selectRandom]] _array;</code> 
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+  seealso= [[selectRandom]], [[selectRandomWeighted]]  
}}  }}  
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−  [[Category:Scripting Commands  +  [[Category:Scripting Commands{{uc:{{PAGENAME}}}}]] 
−  +  {{GameCategoryarma1Scripting Commands}}  
−  +  {{GameCategoryarma2Scripting Commands}}  
−  +  {{GameCategoryarma3Scripting Commands}}  
−  +  {{GameCategorytkohScripting Commands}}  
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<dl class="command_description">  <dl class="command_description">  
+  <dt></dt>  
<dd class="notedate">Posted on July 12, 2015  20:32 (UTC)</dd>  <dd class="notedate">Posted on July 12, 2015  20:32 (UTC)</dd>  
<dt class="note">[[User:HcpookieHcpookie]]</dt>  <dt class="note">[[User:HcpookieHcpookie]]</dt>  
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<code>_Xrnd = round(random 200) 100;</code>  <code>_Xrnd = round(random 200) 100;</code>  
−  
This will yield numbers between 100 and 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.  * 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.<br>To return a whole number use either '''[[round]]''', '''[[ceil]]''' or '''[[floor]]''' together with  +  * 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]]:  
−  +  <code>x = round(random 5) will return 0,1,2,3,4 or 5. (nonuniform 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)</code>  
+  </dd>  
+  <dd class="notedate">Posted on July 22, 2018  12:58 (UTC+2)</dd>  
+  <dt class="note">[[User:Lou MontanaLou Montana]]</dt>  
+  <dd class="note">  
+  {{{!}}class="wikitable"  
+  {{!}}+ 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%  
+  {{!}}}  
</dd>  </dd>  
</dl>  </dl>  
− 
Latest revision as of 01:52, 6 April 2021
Description
 Description:
 Random real (floating point) value from 0 (inclusive) to x (not inclusive).
Since Arma 3 v1.56 alternative syntax is added, allowing the definition of Gaussian Distribution^{[1]} params. Uses the same method as setTriggerTimeout command. Quite useful for spawning loot for example, making more valuable items more rare (Alternative Syntax 1)
Since Arma 3 v1.68 two alternative syntaxes are available: allowing to generate semirandom number based on provided seed (Alternative Syntax 2)
 generating pseudorandom noise texture based on provided seed and returning a single number between 0 (included) and 1 (excluded) at supplied x and y coordinates (Alternative Syntax 3)
Syntax
Alternative Syntax
 Syntax:
 random [min, mid, max] Since Arma 3 v1.55.133393
 Parameters:
 [min, mid, max]: Array
 min: Number
 mid: Number
 max: Number
 Return Value:
 Number
Alternative Syntax 2
 Syntax:
 seed random x Since Arma 3 v1.67.139663
 Parameters:
 seed: Number
 x: Number
 Return Value:
 Number  value from 0 to x
Alternative Syntax 3
 Syntax:
 seed random [x, y] Since Arma 3 v1.67.139663
 Parameters:
 seed: Number
 [x, y]: Array position on the Perlin noise texture
 x: Number
 y: Number
 Return Value:
 Number  value from 0 to 1
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:
 To select random value from an array:
_array = ["apples", "pears", "bananas", "M16"]; _random = _array select floor random count _array; // since Arma 3 v1.55.133393 _random = selectRandom _array;
Additional Information
 See also:
 selectRandomselectRandomWeighted
 Groups:
 Math
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
 Posted on July 12, 2015  20:32 (UTC)
 Hcpookie

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.
x = round(random 5) will return 0,1,2,3,4 or 5. (nonuniform 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)
 Posted on July 22, 2018  12:58 (UTC+2)
 Lou Montana

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%
 ↑ 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.
Categories:
 Scripting Commands
 Introduced with Operation Flashpoint version 1.00
 Operation Flashpoint: New Scripting Commands
 Operation Flashpoint: Scripting Commands
 Command Group: Math
 ArmA: Armed Assault: Scripting Commands
 Arma 2: Scripting Commands
 Arma 3: Scripting Commands
 Take On Helicopters: Scripting Commands