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{{Command|= Comments
{{RV|type=command
____________________________________________________________________________________________


| ofp |= Game name
|game1= ofp
|version1= 1.00


|1.00|= Game version
|game2= ofpe
____________________________________________________________________________________________
|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


____________________________________________________________________________________________
|game4= arma2
|version4= 1.00
 
|game5= arma2oa
|version5= 1.50
 
|game6= tkoh
|version6= 1.00
 
|game7= arma3
|version7= 0.50
 
|gr1= Math
 
|descr= [[File:bellcurve.jpg|thumb|120px|[[#Syntax 2|Syntax&nbsp;2]]'s distribution]]
{{{!}} class="valign-top"
! style="padding-right: 1em; white-space: nowrap" {{!}} {{Link|#Syntax 1}}
{{!}} generates a random floating point value
{{!}}-
! style="padding-right: 1em; 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; white-space: nowrap" {{!}} {{Link|#Syntax 3}}
{{!}} generates a {{Link|https://en.wikipedia.org/wiki/Random_seed|seed-based}} random number
{{!}}-
! style="padding-right: 1em; 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


|'''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
|r1= [[Number]] from 0 (included) to ''x'', '''ex'''cluded
|p21= [min, mid, max]: [[Array]] |=
{{Feature|important|''x'' was accidentally '''in'''cluded due to a bug introduced in {{GVI|arma2|1.00|size= 0.75}} and fixed in {{GVI|arma3|2.18|size= 0.75}}.}}
|p22= min: [[Number]] |=
 
|p23= mid: [[Number]] |=
|s2= [[random]] [min, mid, max]
|p24= max: [[Number]] |=
 
|r2= [[Number]] |= Return value
|s2since= arma3 1.56
 
|p21= min: [[Number]]
 
|p22= mid: [[Number]]
 
|p23= max: [[Number]]
 
|r2= [[Number]] in range from ''min'' to ''max'', weighted by ''mid'' - '''can''' be higher than max (maximum value is {{hl|min + max - mid}})
 
|s3= seed [[random]] x
 
|s3since= arma3 1.68
 
|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''')
 
|p42= x: [[Number]]
 
|r3= [[Number]] from 0 (included) to ''x'' ('''in'''cluded)
 
|s4= seed [[random]] [x, y]


|s3= seed '''random''' x &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(''Since Arma 3 v1.67.139663'')|= Syntax
|s4since= arma3 1.68
|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
|p61= seed: [[Number]]
|p61= seed: [[Number]] |=
|p62= [x, y]: [[Array]] |=
|p63= x: [[Number]] |=
|p64= y: [[Number]] |=
|r4= [[Number]] |= Return value


____________________________________________________________________________________________
|p62= x: [[Number]] - x texture position
 
|x1= <code>_rNumber = [[random]] 1;</code>  |= Example 1


|x2= <code>_rNumber = [[random]] -10;</code>  |= Example 2
|p63= y: [[Number]] - y texture position


|x3= Generate random position inside a circle<code>_center [[getPos]] <nowiki>[</nowiki>[[sqrt]] [[random]] _radius, [[random]] 360];</code>  |= Example 2
|r4= [[Number]] from 0 (included) to 1 ('''ex'''cluded)


|x4= To select random value from an array:
|x1= <sqf>_rNumber = random 1;</sqf>
<code>_array = ["apples", "pears", "bananas", "M16"];
_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
// or since Arma 3 v1.55.133393
_random = [[selectRandom]] _array;</code> |= Example 3


|x4= Compare (each command was executed 100000 times to gather statistics):<code>[[floor]] [[random]] 10;
|x2= <sqf>_rNumber = random -10;</sqf>
// 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];
|x3= Generate a random position inside a circle (see also [[Example Code: Random Area Distribution]])
// 0 - 109 (0%)
<sqf>_center getPos [_radius * sqrt random 1, random 360];</sqf>
// 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];
|x4= Select a random value from an array:
// 0 - 19 (0%)
<sqf>
// 1 - 209 (0%)
_array = ["apples", "pears", "bananas", "M16"];
// 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];
_random = _array select floor random count _array; // before {{arma2}}
// 0 - 11 (0%)
_random = _array call BIS_fnc_selectRandom; // since {{arma2}}
// 1 - 98 (0%)
_random = selectRandom _array; // since {{arma3}} v1.56
// 2 - 430 (0%)
</sqf>
// 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
|x5= Visualisation of {{Link|#Syntax 4}} (warning, it takes a bit to execute and draw):<br>
[[File:A3 random syntax4.png|thumb|right|Result]]
<sqf>
private _parent = call BIS_fnc_displayMission;
if (is3DEN) then { _parent = findDisplay 313 };
private _display = _parent createDisplay "RscDisplayEmpty";
private _background = _disp ctrlCreate ["RscBackground", -1];


}}
private _coef = 0.1;


<h3 style="display:none">Notes</h3>
for "_x" from 1 to 100 do
{
for "_y" from 1 to 100 do
{
private _random = 0 random [_x * _coef, _y * _coef];
private _dot = _display ctrlCreate ["RscBackground", -1];


[[Category:Scripting Commands|RANDOM]]
_dot ctrlSetPosition [0.5 + pixelW * _x, 0.5 + pixelH * _y, pixelW, pixelH];
[[Category:Scripting Commands OFP 1.99|{{uc:{{PAGENAME}}}}]]
_dot ctrlSetBackgroundColor [_random, _random, _random, 1];
[[Category:Scripting Commands OFP 1.96|RANDOM]]
_dot ctrlCommit 0;
[[Category:Scripting Commands OFP 1.46|RANDOM]]
};
[[Category:Scripting Commands ArmA|RANDOM]]
};
[[Category:Command_Group:_Variables|{{uc:{{PAGENAME}}}}]]
</sqf>
[[Category:Scripting Commands ArmA2|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands Arma 3|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting_Commands_Take_On_Helicopters|{{uc:{{PAGENAME}}}}]]


<!-- CONTINUE Notes -->
|seealso= [[selectRandom]] [[selectRandomWeighted]] [[Example Code: Random Area Distribution]]
<dl class="command_description">
}}
<dd class="notedate">Posted on July 12, 2015 - 20:32 (UTC)</dd>
<dt class="note">[[User:Hcpookie|Hcpookie]]</dt>
<dd class="note">
Random selections including negative numbers can be obtained via:


<code>_Xrnd = round(random 200) -100;</code>
{{Note
|user= Hcpookie
|timestamp= 20150712203200
|text= Random selections including negative numbers can be obtained via:
<sqf>_xRnd = round (random 200) - 100;</sqf>


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]]:
<sqf>
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)
</sqf>
}}


* 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.
{{Note
* 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>
|user= Lou Montana
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)
|timestamp= 20180722125800
<br>x=floor(random 5) will return 0,1,2,3 or 4.  (uniform distribution, all numbers have the same probability of being selected)
|text= <nowiki/>
<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)
{{{!}} class="wikitable align-right align-left-col-1 align-center-row-1"
</dd>
{{!}}+ Repartition comparison
</dl>
! Formula
<!-- DISCONTINUE Notes -->
! 0
! 1
! 2
! 3
! 4
! 5
! 6
! 7
! 8
! 9
{{!}}-
{{!}} <sqf>floor random 10</sqf>
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}}-
{{!}} <sqf>floor random [0, 5, 10]</sqf>
{{!}} 0%
{{!}} 2%
{{!}} 7%
{{!}} 17%
{{!}} 25%
{{!}} 25%
{{!}} 17%
{{!}} 7%
{{!}} 2%
{{!}} 0%
{{!}}-
{{!}} <sqf>floor random [0, 10, 0]</sqf>
{{!}} 0%
{{!}} 0%
{{!}} 1%
{{!}} 2%
{{!}} 5%
{{!}} 9%
{{!}} 14%
{{!}} 19%
{{!}} 24%
{{!}} 26%
{{!}}-
{{!}} <sqf>floor random [0, 10, 5]</sqf>
{{!}} 0%
{{!}} 0%
{{!}} 0%
{{!}} 1%
{{!}} 2%
{{!}} 5%
{{!}} 9%
{{!}} 16%
{{!}} 28%
{{!}} 38%
{{!}}}
}}

Latest revision as of 10:21, 13 March 2024

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
x was accidentally included due to a bug introduced in Logo A2.png1.00 and fixed in Arma 3 logo black.png2.18.

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 - can be higher than max (maximum value is min + max - 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 (included)

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:
Visualisation of Syntax 4 (warning, it takes a bit to execute and draw):
Result
private _parent = call BIS_fnc_displayMission; if (is3DEN) then { _parent = findDisplay 313 }; private _display = _parent createDisplay "RscDisplayEmpty"; private _background = _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 = _display ctrlCreate ["RscBackground", -1]; _dot ctrlSetPosition [0.5 + pixelW * _x, 0.5 + pixelH * _y, pixelW, pixelH]; _dot ctrlSetBackgroundColor [_random, _random, _random, 1]; _dot ctrlCommit 0; }; };

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 - c
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 - c
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.