Difference between revisions of "random"

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{{Command|= Comments
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{{RV|type=command
____________________________________________________________________________________________
 
  
| ofp |= Game name
+
|game1= ofp
 +
|version1= 1.00
  
|1.00|= Game version
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|game2= ofpe
____________________________________________________________________________________________
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|version2= 1.00
  
|[[Image:bellcurve.jpg|right|200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br><br>
+
|game3= arma1
Since Arma 3 v1.55.133393 alternative syntax is added, allowing to define [https://en.wikipedia.org/wiki/Normal_distribution Gaussian Distribution] params. Uses the same method as [[setTriggerTimeout]] command. Quite useful for spawning loot for example, making more valuable items more rare.<br><br>
+
|version3= 1.00
Since Arma 3 v1.67.139663 an alternative syntax is available, allowing to generate semi-random number based on provided seed.<br><br>
 
Since Arma 3 v1.67.139663 an alternative syntax is available, 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. |= Description
 
  
____________________________________________________________________________________________
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|game4= arma2
 +
|version4= 1.00
 +
 
 +
|game5= arma2oa
 +
|version5= 1.50
 +
 
 +
|game6= tkoh
 +
|version6= 1.00
 +
 
 +
|game7= arma3
 +
|version7= 0.50
 +
 
 +
|gr1= Math
 +
 
 +
|descr= [[Image:bellcurve.jpg|right|200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br><br>
 +
{{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>
 +
{{GVI|arma3|1.68}} two alternative syntaxes are available:
 +
* allowing to generate {{Wikipedia|Random seed|seed-based}} random number based on provided seed ({{HashLink|#Alternative Syntax 2}})
 +
* 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}})
 +
 
 +
|s1= [[random]] x
  
|'''random''' x |= Syntax
 
 
|p1= x: [[Number]]
 
|p1= x: [[Number]]
| [[Number]] |= Return value
 
  
|s2= '''random''' [min, mid, max] &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.55.133393'')|= Syntax
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|r1= [[Number]]
|p21= [min, mid, max]: [[Array]] |=
+
 
|p22= min: [[Number]] |=
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|s2= [[random]] [min, mid, max] {{Since|arma3|1.56|y}}
|p23= mid: [[Number]] |=
+
 
|p24= max: [[Number]] |=
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|p21= [min, mid, max]: [[Array]]
|r2= [[Number]] |= Return value
+
 
 +
|p22= min: [[Number]]
 +
 
 +
|p23= mid: [[Number]]
  
|s3= seed '''random''' x &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.67.139663'')|= Syntax
+
|p24= max: [[Number]]
|p41= seed: [[Number]] |=
 
|p42= x: [[Number]] |=
 
|r3= [[Number]] |= Return value
 
  
|s4= seed '''random''' [x,y] &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.67.139663'') |= Syntax
+
|r2= [[Number]]
|p61= seed: [[Number]] |=
 
|p62= [x, y]: [[Array]] |=
 
|p63= x: [[Number]] |=
 
|p64= y: [[Number]] |=
 
|r4= [[Number]] |= Return value
 
  
____________________________________________________________________________________________
+
|s3= seed [[random]] x {{Since|arma3|1.68|y}}
 
 
|x1= <code>_rNumber = [[random]] 1;</code>  |= Example 1
 
  
|x2= <code>_rNumber = [[random]] -10;</code>  |= Example 2
+
|p41= 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''')
  
|x3= To select random value from an array:
+
|p42= x: [[Number]]
<code>_array = ["apples", "pears", "bananas", "M16"];
+
 
_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
+
|r3= [[Number]] - Value from 0 to x
// or since Arma 3 v1.55.133393
+
 
_random = [[selectRandom]] _array;</code>  |= Example 3
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|s4= seed [[random]] [x, y] {{Since|arma3|1.68|y}}
 +
 
 +
|p61= seed: [[Number]]
 +
 
 +
|p62= [x, y]: [[Array]] - texture position (''not'' a Perlin noise)
  
|x4= Compare (each command was executed 100000 times to gather statistics):<code>[[floor]] [[random]] 10;
+
|p63= x: [[Number]]
// 0 - 10099 (10%)
 
// 1 - 10040 (10%)
 
// 2 - 10154 (10%)
 
// 3 - 9910 (10%)
 
// 4 - 10023 (10%)
 
// 5 - 9937 (10%)
 
// 6 - 10118 (10%)
 
// 7 - 9716 (10%)
 
// 8 - 9986 (10%)
 
// 9 - 10017 (10%)
 
  
[[floor]] [[random]] [0,5,10];
+
|p64= y: [[Number]]
// 0 - 109 (0%)
 
// 1 - 1604 (2%)
 
// 2 - 6839 (7%)
 
// 3 - 16671 (17%)
 
// 4 - 24706 (25%)
 
// 5 - 24702 (25%)
 
// 6 - 16626 (17%)
 
// 7 - 6925 (7%)
 
// 8 - 1702 (2%)
 
// 9 - 116 (0%)
 
  
[[floor]] [[random]] [0,10,0];
+
|r4= [[Number]] - Value from 0 to 1
// 0 - 19 (0%)
 
// 1 - 209 (0%)
 
// 2 - 817 (1%)
 
// 3 - 2384 (2%)
 
// 4 - 4841 (5%)
 
// 5 - 8976 (9%)
 
// 6 - 14067 (14%)
 
// 7 - 18955 (19%)
 
// 8 - 23605 (24%)
 
// 9 - 26127 (26%)
 
  
[[floor]] [[random]] [0,10,5];
+
|x1= <code>_rNumber = [[random]] 1;</code>
// 0 - 11 (0%)
 
// 1 - 98 (0%)
 
// 2 - 430 (0%)
 
// 3 - 1149 (1%)
 
// 4 - 2384 (2%)
 
// 5 - 4546 (5%)
 
// 6 - 8612 (9%)
 
// 7 - 16283 (16%)
 
// 8 - 28393 (28%)
 
// 9 - 38094 (38%)</code> |= Example 2
 
____________________________________________________________________________________________
 
  
| [[Math Commands]], [[selectRandom]] |= See also
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|x2= <code>_rNumber = [[random]] -10;</code>
  
}}
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|x3= Generate a random position inside a circle (see also [[Example Code: Random Area Distribution]])
 +
<code>_center [[getPos]] [_radius * [[sqrt]] [[random]] 1, [[random]] 360];</code>
  
<h3 style="display:none">Notes</h3>
+
|x4= To select random value from an array:
 +
<code>_array = ["apples", "pears", "bananas", "M16"];
 +
_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
 +
{{cc|{{Since|arma3|1.56}}}}
 +
_random = [[selectRandom]] _array;</code>
  
[[Category:Scripting Commands|RANDOM]]
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|seealso= [[selectRandom]], [[selectRandomWeighted]]
[[Category:Scripting Commands OFP 1.99|{{uc:{{PAGENAME}}}}]]
+
}}
[[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}}}}]]
 
[[Category:Scripting Commands ArmA2|{{uc:{{PAGENAME}}}}]]
 
[[Category:Scripting Commands Arma 3|{{uc:{{PAGENAME}}}}]]
 
[[Category:Scripting_Commands_Take_On_Helicopters|{{uc:{{PAGENAME}}}}]]
 
  
<!-- CONTINUE Notes -->
 
 
<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:Hcpookie|Hcpookie]]</dt>
 
<dt class="note">[[User:Hcpookie|Hcpookie]]</dt>
 
<dd class="note">
 
<dd class="note">
 
Random selections including negative numbers can be obtained via:
 
Random selections including negative numbers can be obtained via:
 
 
<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.
 +
* 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. (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)</code>
 +
</dd>
  
* 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.
+
<dd class="notedate">Posted on July 22, 2018 - 12:58 (UTC+2)</dd>
* 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''':<br>
+
<dt class="note">[[User:Lou Montana|Lou Montana]]</dt>
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)
+
<dd class="note">
<br>x=floor(random 5) will return 0,1,2,3 or 4.  (uniform distribution, all numbers have the same probability of being selected)
+
{| class="wikitable"
<br>x=ceil(random 5) will return  0,1,2,3,4 or 5. (0 is very unlikely, but possible, as ceil 0 is 0)
+
|+ 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>
<!-- DISCONTINUE Notes -->
 

Revision as of 19:54, 17 July 2021

Hover & click on the images for description

Description

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

Arma 3 logo black.png1.56 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)

Arma 3 logo black.png1.68 two alternative syntaxes are available:

Groups:
Math

Syntax 1

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

Syntax 2

Syntax:
random [min, mid, max] Template:Since
Parameters:
[min, mid, max]: Array
min: Number
mid: Number
max: Number
Return Value:
Number

Syntax 3

Syntax:
seed random x Template:Since
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 - Value from 0 to x

Syntax 4

Syntax:
seed random [x, y] Template:Since
Parameters:
seed: Number
[x, y]: Array - texture position (not a Perlin noise)
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; // Template:Since _random = selectRandom _array;

Additional Information

See also:
selectRandomselectRandomWeighted

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.
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.