Package nz.org.riskscape.engine.util

Class RandomUtils

java.lang.Object

nz.org.riskscape.engine.util.RandomUtils

public class RandomUtils
extends Object

Helper functions for generating random numbers or sampling from random distributions.

Constructor Summary

Constructors

Constructor	Description
RandomUtils()

Method Summary

Modifier and Type	Method	Description
static double	getFromRange(double start, double stop)
static List<Double>	getFromRange(double start, double stop, Optional<Long> seed, int numSamples)	Randomly selects a value from the given range.
static double	getNormalVariate(double mean, double stddev)
static List<Double>	getNormalVariate(double mean, double stddev, Optional<Long> seed, int numSamples)	Randomly selects a value from a normal distribution with the given mean and standard deviation.
static Object	pick(List<?> items)
static Object	pick(List<?> items, List<Double> weights)
static Object	pick(List<?> items, List<Double> weights, Optional<Long> seed)	Picks an item based on a weighted random choice.
static Object	pick(List<?> items, Optional<Long> seed)	Picks an item randomly from the given list.

Methods inherited from class java.lang.Object

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

Constructor Details

RandomUtils

public RandomUtils()

Method Details

getNormalVariate

public static List<Double> getNormalVariate(double mean,
 double stddev,
 Optional<Long> seed,
 int numSamples)

Randomly selects a value from a normal distribution with the given mean and standard deviation. This means that values closer to the mean have a higher likelihood of being selected.

getNormalVariate

public static double getNormalVariate(double mean,
 double stddev)

getFromRange

public static List<Double> getFromRange(double start,
 double stop,
 Optional<Long> seed,
 int numSamples)

Randomly selects a value from the given range. Assumes values are uniformly distributed. The range is from start (inclusive) to stop (exclusive).

getFromRange

public static double getFromRange(double start,
 double stop)

pick

public static Object pick(List<?> items,
 List<Double> weights,
 Optional<Long> seed)

Picks an item based on a weighted random choice.

Parameters:

items - the items to choose from

weights - the weighted probabilities

pick

public static Object pick(List<?> items,
 List<Double> weights)

pick

public static Object pick(List<?> items,
 Optional<Long> seed)

Picks an item randomly from the given list.

pick

public static Object pick(List<?> items)