Difference between revisions of "random"

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m (Clarified ceil roudning usage)
m (Corrected distribution)
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{{Command|= Comments
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{{Command|Comments=
 
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| ofp |= Game name
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| ofp |Game name=
  
|1.00|= Game version
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|1.00|Game version=
 
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| Random real value from 0 (inclusive) to x (not inclusive). |= Description
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|[[Image:bellcurve.jpg|right|200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br />
 +
<br />
 +
Since Arma 3 v1.55.133393 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 v1.67.139663 two alternative syntaxes are available:
 +
* allowing to generate semi-random number based on provided seed ('''Alternative Syntax 2''')
 +
* generating pseudo-random [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''') |Description=
 
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| [[Number]] <nowiki>=</nowiki> '''random''' [[Number]] |= Syntax
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| [[random]] x |Syntax=
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|p1= x: [[Number]]
 +
| [[Number]] |Return value=
  
| [[Number]] |= Return value
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|s2= [[random]] [min, mid, max] &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.55.133393'')|Syntax 2=
 +
|p21= [min, mid, max]: [[Array]] |Parameter 21=
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|p22= min: [[Number]] |Parameter 22=
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|p23= mid: [[Number]] |Parameter 23=
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|p24= max: [[Number]] |Parameter 24=
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|r2= [[Number]] |Return value 2=
 +
 
 +
|s3= seed [[random]] x &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.67.139663'')|Syntax 3=
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|p41= seed: [[Number]] |Parameter 41=
 +
|p42= x: [[Number]] |Parameter 42=
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|r3= [[Number]] |Return value 3=
 +
 
 +
|s4= seed [[random]] [x, y] &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.67.139663'') |Syntax 4=
 +
|p61= seed: [[Number]] |Parameter 61=
 +
|p62= [x, y]: [[Array]] position on the [https://en.wikipedia.org/wiki/Perlin_noise Perlin noise texture] |Parameter 62=
 +
|p63= x: [[Number]] |Parameter 63=
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|p64= y: [[Number]] |Parameter 64=
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|r4= [[Number]] |Return value 4=
 
____________________________________________________________________________________________
 
____________________________________________________________________________________________
 
   
 
   
|x1= <pre>_rNumber = random 1</pre> |= Example 1
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|x1= <code>_rNumber = [[random]] 1;</code> |Example 1=
 +
 
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|x2= <code>_rNumber = [[random]] -10;</code> |Example 2=
 +
 
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|x3= Generate random position inside a circle
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<code>_center [[getPos]] <nowiki>[</nowiki>_radius * [[sqrt]] [[random]] 1, [[random]] 360];</code> |Example 3=
 +
 
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|x4= To select random value from an array:
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<code>_array = ["apples", "pears", "bananas", "M16"];
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_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
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{{codecomment|// since Arma 3 v1.55.133393}}
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_random = [[selectRandom]] _array;</code>  |Example 4=
 
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| [[Math Commands]] |= See also
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| [[Math Commands]], [[selectRandom]], [[selectRandomWeighted]] |See also=
 
 
 
}}
 
}}
  
 
<h3 style="display:none">Notes</h3>
 
<h3 style="display:none">Notes</h3>
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[[Category:Scripting Commands|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting Commands OFP 1.46|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting Commands OFP 1.96|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting Commands OFP 1.99|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting Commands ArmA|{{uc:{{PAGENAME}}}}]]
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[[Category:Command_Group:_Variables|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting Commands ArmA2|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting_Commands_Take_On_Helicopters|{{uc:{{PAGENAME}}}}]]
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[[Category:Scripting Commands Arma 3|{{uc:{{PAGENAME}}}}]]
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<!-- CONTINUE Notes -->
 
<dl class="command_description">
 
<dl class="command_description">
<!-- Note Section BEGIN -->
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<dd class="notedate">Posted on July 12, 2015 - 20:32 (UTC)</dd>
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<dt class="note">[[User:Hcpookie|Hcpookie]]</dt>
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<dd class="note">
 +
Random selections including negative numbers can be obtained via:
  
 +
<code>_Xrnd = round(random 200) -100;</code>
 +
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 '''[[ceil]]''' or '''[[floor]]''' together with '''random'''.<br>
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* The number returned is unlikely to be a whole number.<br />
x=floor(random 5) will return 0,1,2,3 or 4.
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To return a whole number use either '''[[round]]''', '''[[ceil]]''' or '''[[floor]]''' together with [[random]]:
x=ceil(random 5) will return 0, 1,2,3,4 or 5. (0 is unlikely, but possible, as ceil 0 is 0)
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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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x = floor(random 5) will return 0,1,2,3 or 4.   (uniform distribution, all numbers have the same probability of being selected)
<!-- Note Section END -->
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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>
 +
</dd>
 +
<dd class="notedate">Posted on July 22, 2018 - 12:58 (UTC+2)</dd>
 +
<dt class="note">[[User:Lou Montana|Lou Montana]]</dt>
 +
<dd class="note">
 +
{{{!}}class="bikitable"
 +
{{!}}+ Repartition comparison
 +
! Formula
 +
! 0
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! 1
 +
! 2
 +
! 3
 +
! 4
 +
! 5
 +
! 6
 +
! 7
 +
! 8
 +
! 9
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{{!}}-
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{{!}} [[floor]] [[random]] 10;
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{{!}} 10%
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{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}} 10%
 +
{{!}}-
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{{!}} [[floor]] [[random]] [0, 5, 10]
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{{!}} 0%
 +
{{!}} 2%
 +
{{!}} 7%
 +
{{!}} 17%
 +
{{!}} 25%
 +
{{!}} 25%
 +
{{!}} 17%
 +
{{!}} 7%
 +
{{!}} 2%
 +
{{!}} 0%
 +
{{!}}-
 +
{{!}} [[floor]] [[random]] [0, 10, 0]
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{{!}} 0%
 +
{{!}} 0%
 +
{{!}} 1%
 +
{{!}} 2%
 +
{{!}} 5%
 +
{{!}} 9%
 +
{{!}} 14%
 +
{{!}} 19%
 +
{{!}} 24%
 +
{{!}} 26%
 +
{{!}}-
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{{!}} [[floor]] [[random]] [0, 10, 5]
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{{!}} 0%
 +
{{!}} 0%
 +
{{!}} 0%
 +
{{!}} 1%
 +
{{!}} 2%
 +
{{!}} 5%
 +
{{!}} 9%
 +
{{!}} 16%
 +
{{!}} 28%
 +
{{!}} 38%
 +
{{!}}}
 +
</dd>
 
</dl>
 
</dl>
 
+
<!-- DISCONTINUE Notes -->
<h3 style="display:none">Bottom Section</h3>
 
 
 
[[Category:Scripting Commands|RANDOM]]
 
[[Category:Scripting Commands OFP 1.96|RANDOM]]
 
[[Category:Scripting Commands OFP 1.46|RANDOM]]
 
[[Category:Scripting Commands ArmA|RANDOM]]
 
[[Category:Command_Group:_Variables|{{uc:{{PAGENAME}}}}]]
 

Revision as of 14:21, 8 March 2019

Introduced with Operation Flashpoint version 1.00
  

Click on the images for descriptions

Introduced in

Game:
Operation Flashpoint
Version:
1.00

Description

Description:
bellcurve.jpg
Random real (floating point) value from 0 (inclusive) to x (not inclusive).


Since Arma 3 v1.55.133393 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 v1.67.139663 two alternative syntaxes are available:

  • allowing to generate semi-random number based on provided seed (Alternative Syntax 2)
  • generating pseudo-random 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

Syntax:
random x
Parameters:
x: Number
Return Value:
Number

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

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

Examples

Example 1:
_rNumber = random 1;
Example 2:
_rNumber = random -10;
Example 3:
Generate random position inside a circle _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

Multiplayer:
-
See also:
Math CommandsselectRandomselectRandomWeighted

Notes

Only post proven facts here. Report bugs on the feedback tracker. Use the talk page or the forums for discussions.
Add New Note | How To

Notes

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.
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)
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%
  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.