random: Difference between revisions

Revision as of 00:07, 18 August 2021

1.00

1.50

1.00

0.50

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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)

1.56

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

1.68

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)

1.68

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:: selectRandom selectRandomWeighted

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%

↑ 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.

[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.

[1]