random

1.001.001.001.001.501.000.50

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Description

Description:

Syntax 2's distribution

Syntax 1	generates a random floating point value
Syntax 2	generates a Gaussian Distribution. 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 1.00 and fixed in 2.18.

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

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:

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_rNumber = random 1;

Example 2:

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_rNumber = random -10;

Example 3:

Generate a random position inside a circle (see also Example Code: Random Area Distribution)

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_center getPos [_radius * sqrt random 1, random 360];

Example 4:

Select a random value from an array:

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_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

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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:

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_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:

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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
Copy floor random 10	10%	10%	10%	10%	10%	10%	10%	10%	10%	10%
Copy floor random [0, 5, 10]	0%	2%	7%	17%	25%	25%	17%	7%	2%	0%
Copy floor random [0, 10, 0]	0%	0%	1%	2%	5%	9%	14%	19%	24%	26%
Copy floor random [0, 10, 5]	0%	0%	0%	1%	2%	5%	9%	16%	28%	38%