random: Difference between revisions

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m (Some wiki formatting)
(Fix description and examples)
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|gr1= Math
|gr1= Math


|descr= [[Image:bellcurve.jpg|right|200px]] Random real (floating point) value from 0 (inclusive) to x (not inclusive).<br><br>
|descr= [[Image:bellcurve.jpg|thumb|120px|[[#Syntax 2|Syntax&nbsp;2]]'s distribution]]
{{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:
! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}} {{HashLink|#Syntax 1}}
* allowing to generate {{Wikipedia|Random seed|seed-based}} random number based on provided seed ({{HashLink|#Alternative Syntax 2}})
{{!}} generates a random floating point value
* 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}})
{{!}}-
! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}}  {{HashLink|#Syntax 2}}
{{!}} generates a {{Wikipedia|Normal_distribution|Gaussian Distribution}}<ref>Technically, it is a rescaled {{Wikipedia|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; vertical-align: top; white-space: nowrap" {{!}}  {{HashLink|#Syntax 3}}
{{!}} generates a {{Wikipedia|Random seed|seed-based}} random number
{{!}}-
! style="padding-right: 1em; vertical-align: top; white-space: nowrap" {{!}}  {{HashLink|#Syntax 4}}
{{!}} generates a {{Wikipedia|Random seed|seed-based}} random noise ('''not''' Perlin) texture based on provided seed and returning the value at supplied coordinates
{{!}}}


|s1= [[random]] x
|s1= [[random]] x
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|p1= x: [[Number]]
|p1= x: [[Number]]


|r1= [[Number]]
|r1= [[Number]] from 0 (included) to ''x'' (excluded)


|s2= [[random]] [min, mid, max]
|s2= [[random]] [min, mid, max]
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|s2since= arma3 1.56
|s2since= arma3 1.56


|p21= [min, mid, max]: [[Array]]
|p21= min: [[Number]]


|p22= min: [[Number]]
|p22= mid: [[Number]]


|p23= mid: [[Number]]
|p23= max: [[Number]]


|p24= max: [[Number]]
|r2= [[Number]] in range from ''min'' to ''max'', weighted by ''mid''
 
|r2= [[Number]]


|s3= seed [[random]] x
|s3= seed [[random]] x
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|p42= x: [[Number]]
|p42= x: [[Number]]


|r3= [[Number]] - Value from 0 to x
|r3= [[Number]] from 0 (included) to ''x'' (excluded)


|s4= seed [[random]] [x, y]
|s4= seed [[random]] [x, y]
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|p61= seed: [[Number]]
|p61= seed: [[Number]]


|p62= [x, y]: [[Array]] - texture position (''not'' a Perlin noise)
|p62= x: [[Number]] - x texture position


|p63= x: [[Number]]
|p63= y: [[Number]] - y texture position


|p64= y: [[Number]]
|r4= [[Number]] from 0 (included) to 1 (excluded)
 
|r4= [[Number]] - Value from 0 to 1


|x1= <code>_rNumber = [[random]] 1;</code>
|x1= <code>_rNumber = [[random]] 1;</code>
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<code>_center [[getPos]] [_radius * [[sqrt]] [[random]] 1, [[random]] 360];</code>
<code>_center [[getPos]] [_radius * [[sqrt]] [[random]] 1, [[random]] 360];</code>


|x4= To select random value from an array:
|x4= Select a random value from an array:
<code>_array = ["apples", "pears", "bananas", "M16"];
<code>_array = ["apples", "pears", "bananas", "M16"];
_random = _array [[select]] [[floor]] [[random]] [[count]] _array;
 
{{cc|Since {{arma3}} v1.56}}
_random = _array [[select]] [[floor]] [[random]] [[count]] _array; {{cc|Before {{arma2}}}}
_random = [[selectRandom]] _array;</code>
_random = _array [[call]] [[BIS_fnc_selectRandom]]; {{cc|Since {{arma2}}}}
_random = [[selectRandom]] _array; {{cc|Since {{arma3}} v1.56}}</code>


|seealso= [[selectRandom]], [[selectRandomWeighted]]
|seealso= [[selectRandom]], [[selectRandomWeighted]]

Revision as of 23:07, 17 August 2021

Logo A0.png1.00ofpe logo.png1.00Logo A1 black.png1.00Logo A2.png1.00A2 OA Logo.png1.50tkoh logo small.png1.00Arma 3 logo black.png0.50
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)

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

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 (excluded)

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

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.
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