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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


|gr1= Math |GROUP1=
|game3= arma1
____________________________________________________________________________________________
|version3= 1.00


|[[Image:bellcurve.jpg|right|200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br>
|game4= arma2
<br>
|version4= 1.00
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=
____________________________________________________________________________________________


| [[random]] x |Syntax=
|game5= arma2oa
|version5= 1.50


|p1= x: [[Number]] |Parameter 1=
|game6= tkoh
|version6= 1.00


| [[Number]] |Return value=
|game7= arma3
____________________________________________________________________________________________
|version7= 0.50


|s2= [[random]] [min, mid, max] {{since|arma3|1.55.133393|y}} |Syntax 2=
|gr1= Math
|p21= [min, mid, max]: [[Array]] |Parameter 21=
|p22= min: [[Number]] |Parameter 22=
|p23= mid: [[Number]] |Parameter 23=
|p24= max: [[Number]] |Parameter 24=
|r2= [[Number]]|Return value 2=
____________________________________________________________________________________________


|s3= seed [[random]] x {{since|arma3|1.67.139663|y}} |Syntax 3=
|descr= [[File:bellcurve.jpg|thumb|120px|[[#Syntax 2|Syntax&nbsp;2]]'s distribution]]
|p41= seed: [[Number]] |Parameter 41=
{{{!}} class="valign-top"
|p42= x: [[Number]] |Parameter 42=
! style="padding-right: 1em; white-space: nowrap" {{!}} {{Link|#Syntax 1}}
|r3= [[Number]] - value from 0 to x |Return value 3=
{{!}} 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
 
|p1= x: [[Number]]
 
|r1= [[Number]] from 0 (included) to ''x'', '''ex'''cluded
{{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}}.}}
 
|s2= [[random]] [min, mid, max]
 
|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]
 
|s4since= arma3 1.68
 
|p61= seed: [[Number]]
 
|p62= x: [[Number]] - x texture position
 
|p63= y: [[Number]] - y texture position
 
|r4= [[Number]] from 0 (included) to 1 ('''ex'''cluded)


|s4= seed [[random]] [x, y] {{since|arma3|1.67.139663|y}} |Syntax 4=
|x1= <sqf>_rNumber = random 1;</sqf>
|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=
|p64= y: [[Number]] |Parameter 64=
|r4= [[Number]] - value from 0 to 1 |Return value 4=
____________________________________________________________________________________________
 
|x1= <code>_rNumber = [[random]] 1;</code> |Example 1=


|x2= <code>_rNumber = [[random]] -10;</code> |Example 2=
|x2= <sqf>_rNumber = random -10;</sqf>


|x3= Generate a random position inside a circle (see also [[Example Code: Random Area Distribution]])
|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> |Example 3=
<sqf>_center getPos [_radius * sqrt random 1, random 360];</sqf>
 
|x4= Select a random value from an array:
<sqf>
_array = ["apples", "pears", "bananas", "M16"];
 
_random = _array select floor random count _array; // before {{arma2}}
_random = _array call BIS_fnc_selectRandom; // since {{arma2}}
_random = selectRandom _array; // since {{arma3}} v1.56
</sqf>
 
|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];


|x4= To select random value from an array:
private _coef = 0.1;
<code>_array = ["apples", "pears", "bananas", "M16"];
_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
{{cc|{{since|arma3|1.55.133393}}}}
_random = [[selectRandom]] _array;</code>  |Example 4=
____________________________________________________________________________________________


| [[selectRandom]], [[selectRandomWeighted]] |See also=
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];


<h3 style="display:none">Notes</h3>
_dot ctrlSetPosition [0.5 + pixelW * _x, 0.5 + pixelH * _y, pixelW, pixelH];
_dot ctrlSetBackgroundColor [_random, _random, _random, 1];
_dot ctrlCommit 0;
};
};
</sqf>


[[Category:Scripting Commands|{{uc:{{PAGENAME}}}}]]
|seealso= [[selectRandom]] [[selectRandomWeighted]] [[Example Code: Random Area Distribution]]
[[Category:Scripting Commands OFP 1.46|{{uc:{{PAGENAME}}}}]]
}}
[[Category:Scripting Commands OFP 1.96|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands OFP 1.99|{{uc:{{PAGENAME}}}}]]
{{GameCategory|arma1|Scripting Commands}}
[[Category:Scripting Commands Arma 2|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands Arma 3|{{uc:{{PAGENAME}}}}]]
[[Category:Scripting Commands Take On Helicopters|{{uc:{{PAGENAME}}}}]]


<!-- CONTINUE Notes -->
{{Note
<dl class="command_description">
|user= Hcpookie
<dd class="notedate">Posted on July 12, 2015 - 20:32 (UTC)</dd>
|timestamp= 20150712203200
<dt class="note">[[User:Hcpookie|Hcpookie]]</dt>
|text= Random selections including negative numbers can be obtained via:
<dd class="note">
<sqf>_xRnd = round (random 200) - 100;</sqf>
Random selections including negative numbers can be obtained via:


<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>
* 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]]:
<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)
<sqf>
x = floor(random 5) will return 0,1,2,3 or 4.   (uniform distribution, all numbers have the same probability of being selected)
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 = ceil(random 5) will return 0,1,2,3,4 or 5. (0 is very unlikely, but possible, as ceil 0 is 0)</code>
x = floor (random 5) // will return 0, 1, 2, 3 or 4. (uniform distribution, all numbers have the same probability of being selected)
</dd>
x = ceil (random 5) // will return 0, 1, 2, 3, 4 or 5. (0 is very unlikely, but possible, as ceil 0 is 0)
<dd class="notedate">Posted on July 22, 2018 - 12:58 (UTC+2)</dd>
</sqf>
<dt class="note">[[User:Lou Montana|Lou Montana]]</dt>
}}
<dd class="note">
 
{{{!}}class="wikitable"
{{Note
|user= Lou Montana
|timestamp= 20180722125800
|text= <nowiki/>
{{{!}} class="wikitable align-right align-left-col-1 align-center-row-1"
{{!}}+ Repartition comparison
{{!}}+ Repartition comparison
! Formula
! Formula
Line 107: Line 160:
! 9
! 9
{{!}}-
{{!}}-
{{!}} [[floor]] [[random]] 10;
{{!}} <sqf>floor random 10</sqf>
{{!}} 10%
{{!}} 10%
{{!}} 10%
{{!}} 10%
Line 119: Line 172:
{{!}} 10%
{{!}} 10%
{{!}}-
{{!}}-
{{!}} [[floor]] [[random]] [0, 5, 10]
{{!}} <sqf>floor random [0, 5, 10]</sqf>
{{!}} 0%
{{!}} 0%
{{!}} 2%
{{!}} 2%
Line 131: Line 184:
{{!}} 0%
{{!}} 0%
{{!}}-
{{!}}-
{{!}} [[floor]] [[random]] [0, 10, 0]
{{!}} <sqf>floor random [0, 10, 0]</sqf>
{{!}} 0%
{{!}} 0%
{{!}} 0%
{{!}} 0%
Line 143: Line 196:
{{!}} 26%
{{!}} 26%
{{!}}-
{{!}}-
{{!}} [[floor]] [[random]] [0, 10, 5]
{{!}} <sqf>floor random [0, 10, 5]</sqf>
{{!}} 0%
{{!}} 0%
{{!}} 0%
{{!}} 0%
Line 155: Line 208:
{{!}} 38%
{{!}} 38%
{{!}}}
{{!}}}
</dd>
}}
</dl>
<!-- DISCONTINUE Notes -->

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.