mikera.util

Class Rand

java.lang.Object

mikera.util.Rand

public final class Rand
extends java.lang.Object

Constructor Summary

Constructors

Constructor and Description
Rand()

Method Summary

Modifier and Type	Method and Description
static int	best(int r, int n, int s) sum of best r from n s-sided dice
static double	binary(double mean)
static void	binarySample(double[] temp, int offset, int length) Randomises the temp array to 0.0 or 1.0 according to the probabilities in the array
static void	binarySample(float[] temp, int offset, int length)
static double	binomialChance(int r, int n, double p)
static boolean	chance(double d) Returns true with a given probability
static boolean	chance(float d) Returns true with a given probability
static void	chooseIntegers(int[] dest, int destOffset, int length, int maxValue) Chooses a set of distinct integers from a range 0 to maxValue-1 Resulting integers are sorted
static double	combinations(int r, int n)
static double	cumulativeBinomialChance(int r, int n, double p) Returns the probability of up to r successes in n trials, each with probability of success p
static int	d(int sides) simulates a dice roll with the given number of sides
static int	d(int number, int sides) Calculates the sum of (number) x (sides)-sided dice
static int	d10()
static int	d100()
static int	d12()
static int	d20()
static int	d3()
static int	d4()
static int	d6()
static int	d8()
static double	exp(double mean) Returns a random sample from an exponential distribution
static double	factorial(int n)
static double	factorialRatio(int n, int r) Calculates n!/r! Avoids the overhead of calculating the terms which cancel out
static void	fillBinary(double[] data, int start, int length, double mean)
static void	fillBinary(float[] d, int start, int length)
static void	fillGaussian(double[] d, int start, int length, double u, double sd)
static void	fillGaussian(float[] d, int start, int length, float u, float sd)
static void	fillUniform(float[] d, int start, int length)
static int	geom(double p) Returns a sample from a Geometric distribution Discrete distribution with decay rate p Mean = (1-p) / p Probability mass function for each integer output k = p.(1-p)^k
static int	indexFromWeights(double[] probabilities)
static double	n(double u, double sd) Generates a normal distributed number with the given mean and standard deviation
static boolean	nextBoolean() Sample a random boolean value with 50% chance
static byte	nextByte() Sample a random (signed) byte
static char	nextChar() Sample a random char
static double	nextDouble() Returns standard double in range [0..1)
static float	nextFloat() Sample a random float in range [0..1)
static double	nextGaussian()
static int	nextInt() Sample a random signed 32-bit integer
static char	nextLetter() Sample a random lowercase letter
static java.lang.String	nextLetterString(int length)
static long	nextLong() Gets a long random value
static short	nextShort() Sample a random signed short value
static java.lang.String	nextString()
static int	otherIndex(int i, int max) Return a random index between 0 and max (exclusive) not equal to i
static <T> T	pick(java.util.Collection<T> ts) Picks a random item from a given collection
static <T> T	pick(java.util.List<T> ts) Picks a random item from a given list
static <T> T	pick(T[] ts) Picks a random item from a given array
static int	po(double mean) Poisson distribution
static int	po(int numerator, int denominator) Draw a sample from the possion distribution with parameter = numerator / denominator
static int	r(int s) Random number from zero to s-1
static void	randIntegers(int[] dest, int destOffset, int length, int maxValue) Creates a set of n random integers from a range of 0 to maxValue-1
static int	range(int n1, int n2) Returns random number uniformly distributed in inclusive [n1, n2] range.
static int	round(double d) Randomly rounds to the nearest integer
static <T> void	shuffle(T[] ts) Randomly shuffles all elements in a given array
static int	sig(float x) logistic sigmoid probability
static double	sigmoid(double a) Sigmoid function
static double	u() Sample a random uniform double in range [0..1)
static double	u(double max) Sample a random uniform double in range [0..max)
static double	u(double min, double max) Sample a random uniform double in the range [min..max)
static int	xorShift32(int a) XORShift algorithm - credit to George Marsaglia!
static long	xorShift64(long a) XORShift algorithm - very fast psuedo-random number generator Credit to George Marsaglia!

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Rand

public Rand()

Method Detail

nextLong

public static final long nextLong()

Gets a long random value

Returns:

Random long value based on static state

xorShift64

public static final long xorShift64(long a)

XORShift algorithm - very fast psuedo-random number generator Credit to George Marsaglia!

Parameters:

a - Initial state

Returns:

new state

xorShift32

public static final int xorShift32(int a)

XORShift algorithm - credit to George Marsaglia!

Parameters:

a - Initial state

Returns:

new state

chance

public static boolean chance(double d)

Returns true with a given probability

Parameters:

d -

Returns:

chance

public static boolean chance(float d)

Returns true with a given probability

Parameters:

d -

Returns:

best

public static int best(int r,
                       int n,
                       int s)

sum of best r from n s-sided dice

Parameters:

r -

n -

s -

Returns:

sigmoid

public static double sigmoid(double a)

Sigmoid function

sig

public static int sig(float x)

logistic sigmoid probability

Parameters:

x -

Returns:

po

public static int po(double mean)

Poisson distribution

Parameters:

mean - The mean of the poisson distrubution to sample from

Returns:

po

public static int po(int numerator,
                     int denominator)

Draw a sample from the possion distribution with parameter = numerator / denominator

Parameters:

numerator -

denominator -

Returns:

d

public static int d(int number,
                    int sides)

Calculates the sum of (number) x (sides)-sided dice

Parameters:

number -

sides -

Returns:

factorial

public static double factorial(int n)

factorialRatio

public static double factorialRatio(int n,
                                    int r)

Calculates n!/r! Avoids the overhead of calculating the terms which cancel out

Parameters:

n -

r -

Returns:

cumulativeBinomialChance

public static double cumulativeBinomialChance(int r,
                                              int n,
                                              double p)

Returns the probability of up to r successes in n trials, each with probability of success p

Parameters:

r -

n -

p -

Returns:

combinations

public static double combinations(int r,
                                  int n)

binomialChance

public static double binomialChance(int r,
                                    int n,
                                    double p)

exp

public static double exp(double mean)

Returns a random sample from an exponential distribution

Parameters:

mean -

Returns:

geom

public static int geom(double p)

Returns a sample from a Geometric distribution Discrete distribution with decay rate p Mean = (1-p) / p Probability mass function for each integer output k = p.(1-p)^k

nextInt

public static final int nextInt()

Sample a random signed 32-bit integer

Returns:

nextShort

public static final short nextShort()

Sample a random signed short value

Returns:

nextChar

public static final char nextChar()

Sample a random char

Returns:

nextLetterString

public static final java.lang.String nextLetterString(int length)

nextByte

public static final byte nextByte()

Sample a random (signed) byte

Returns:

nextBoolean

public static boolean nextBoolean()

Sample a random boolean value with 50% chance

Returns:

nextLetter

public static final char nextLetter()

Sample a random lowercase letter

Returns:

r

public static final int r(int s)

Random number from zero to s-1

Parameters:

s - Upper bound (excluded)

Returns:

otherIndex

public static final int otherIndex(int i,
                                   int max)

Return a random index between 0 and max (exclusive) not equal to i

nextDouble

public static final double nextDouble()

Returns standard double in range [0..1)

Returns:

nextFloat

public static final float nextFloat()

Sample a random float in range [0..1)

Returns:

u

public static final double u()

Sample a random uniform double in range [0..1)

Returns:

u

public static final double u(double max)

Sample a random uniform double in range [0..max)

Parameters:

max -

Returns:

u

public static final double u(double min,
                             double max)

Sample a random uniform double in the range [min..max)

Parameters:

min -

max -

Returns:

round

public static final int round(double d)

Randomly rounds to the nearest integer

range

public static final int range(int n1,
                              int n2)

Returns random number uniformly distributed in inclusive [n1, n2] range. It is allowed to have to n1 > n2, or n1 < n2, or n1 == n2.

d

public static final int d(int sides)

simulates a dice roll with the given number of sides

Parameters:

sides -

Returns:

d3

public static final int d3()

d4

public static final int d4()

d6

public static final int d6()

d8

public static final int d8()

d10

public static final int d10()

d12

public static final int d12()

d20

public static final int d20()

d100

public static final int d100()

n

public static double n(double u,
                       double sd)

Generates a normal distributed number with the given mean and standard deviation

Parameters:

u - Mean

sd - Standard deviation

Returns:

nextGaussian

public static double nextGaussian()

nextString

public static java.lang.String nextString()

shuffle

public static <T> void shuffle(T[] ts)

Randomly shuffles all elements in a given array

chooseIntegers

public static void chooseIntegers(int[] dest,
                                  int destOffset,
                                  int length,
                                  int maxValue)

Chooses a set of distinct integers from a range 0 to maxValue-1 Resulting integers are sorted

randIntegers

public static void randIntegers(int[] dest,
                                int destOffset,
                                int length,
                                int maxValue)

Creates a set of n random integers from a range of 0 to maxValue-1

pick

public static <T> T pick(T[] ts)

Picks a random item from a given array

pick

public static <T> T pick(java.util.List<T> ts)

Picks a random item from a given list

pick

public static <T> T pick(java.util.Collection<T> ts)

Picks a random item from a given collection

fillUniform

public static void fillUniform(float[] d,
                               int start,
                               int length)

fillBinary

public static void fillBinary(float[] d,
                              int start,
                              int length)

fillGaussian

public static void fillGaussian(float[] d,
                                int start,
                                int length,
                                float u,
                                float sd)

fillGaussian

public static void fillGaussian(double[] d,
                                int start,
                                int length,
                                double u,
                                double sd)

fillBinary

public static void fillBinary(double[] data,
                              int start,
                              int length,
                              double mean)

binary

public static double binary(double mean)

binarySample

public static void binarySample(float[] temp,
                                int offset,
                                int length)

binarySample

public static void binarySample(double[] temp,
                                int offset,
                                int length)

Randomises the temp array to 0.0 or 1.0 according to the probabilities in the array

Parameters:

temp -

offset -

length -

indexFromWeights

public static int indexFromWeights(double[] probabilities)