/// <summary>
/// Sample from the provided discrete probability distribution.
/// </summary>
/// <param name="dist">The discrete distribution to sample from.</param>
/// <param name="rng">Random number generator.</param>
public static int Sample(DiscreteDistribution dist, XorShiftRandom rng)
{
// Throw the ball and return an integer indicating the outcome.
double sample = rng.NextDouble();
double acc = 0.0;
for(int i=0; i<dist.Probabilities.Length; i++)
{
acc += dist.Probabilities[i];
if(sample < acc) {
return dist.Labels[i];
}
}
// We might get here through floating point arithmetic rounding issues.
// e.g. accumulator == throwValue.
// Find a nearby non-zero probability to select.
// Wrap around to start of array.
for(int i=0; i<dist.Probabilities.Length; i++)
{
if(0.0 != dist.Probabilities[i]) {
return dist.Labels[i];
}
}
// If we get here then we have an array of zero probabilities.
throw new InvalidOperationException("Invalid operation. No non-zero probabilities to select.");
}
public void NextBytes()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
byte[] sampleArr = new byte[sampleCount];
rng.NextBytes(sampleArr);
NextByteInner(sampleArr);
}
/// <summary>
/// Constructs with the provided world parameter arguments.
/// </summary>
public PreyCaptureWorld(int gridSize, int preyInitMoves, double preySpeed, double sensorRange, int maxTimesteps)
{
_gridSize = gridSize;
_preyInitMoves = preyInitMoves;
_preySpeed = preySpeed;
_sensorRange = sensorRange;
_maxTimesteps = maxTimesteps;
_rng = new XorShiftRandom();
}
public void NextByte()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
byte[] sampleArr = new byte[sampleCount];
for(int i=0; i<sampleCount; i++){
sampleArr[i] = rng.NextByte();
}
NextByteInner(sampleArr);
}
public void NextDouble()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
double[] sampleArr = new double[sampleCount];
for(int i=0; i<sampleCount; i++){
sampleArr[i] = rng.NextDouble();
}
UniformDistributionTest(sampleArr, 0.0, 1.0);
}
public void NextBool()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
int trueCount = 0, falseCount = 0;
double maxExpectedCountErr = sampleCount / 25.0;
for(int i=0; i<sampleCount; i++) {
if(rng.NextBool()) trueCount++; else falseCount++;
}
double countErr = Math.Abs(trueCount - falseCount);
if(countErr > maxExpectedCountErr) Assert.Fail();
}
public void TestWriteZeroBytes()
{
byte[] buf = new byte[0];
MemoryBlockStream ms = new MemoryBlockStream();
ms.Write(buf, 0, 0);
Assert.AreEqual(ms.Length, 0);
XorShiftRandom rng = new XorShiftRandom(1234567);
byte[] buf2 = new byte[100];
rng.NextBytes(buf2);
ms.Write(buf2, 0, buf2.Length);
if(!Utils.AreEqual(ms.ToArray(), buf2)) Assert.Fail();
ms.Write(buf, 0, 0);
Assert.AreEqual(ms.Length, buf2.Length);
}
/// <summary>
/// Genetic mutation for auxiliary argument data.
/// </summary>
public void MutateAuxArgs(double[] auxArgs, XorShiftRandom rng, ZigguratGaussianSampler gaussianSampler, double connectionWeightRange)
{
// Mutate center.
// Add gaussian ditribution sample and clamp result to +-connectionWeightRange.
double tmp = auxArgs[0] + gaussianSampler.NextSample(0, _auxArgsMutationSigmaCenter);
if(tmp < -connectionWeightRange) {
auxArgs[0] = -connectionWeightRange;
}
else if(tmp > connectionWeightRange) {
auxArgs[0] = connectionWeightRange;
}
else {
auxArgs[0] = tmp;
}
// Mutate radius.
// Add gaussian ditribution sample and clamp result to [0,1]
tmp = auxArgs[1] + gaussianSampler.NextSample(0, _auxArgsMutationSigmaRadius);
if(tmp < 0.0) {
auxArgs[1] = 0.0;
}
else if(tmp > 1.0) {
auxArgs[1] = 1.0;
}
else {
auxArgs[1] = tmp;
}
}
/// <summary>
/// For activation functions that accept auxiliary arguments; generates random initial values for aux arguments for newly
/// added nodes (from an 'add neuron' mutation).
/// </summary>
public double[] GetRandomAuxArgs(XorShiftRandom rng, double connectionWeightRange)
{
double[] auxArgs = new double[2];
auxArgs[0] = (rng.NextDouble()-0.5) * 2.0;
auxArgs[1] = rng.NextDouble();
return auxArgs;
}
/// <summary>
/// Constructor accepting a trackLength parameter (length of the track that the walker is walking along).
/// </summary>
/// <param name="trackLength"></param>
/// <param name="rng">Random number generator.</param>
public WalkerWorld(XorShiftRandom rng, float trackLength)
{
_rng = rng;
_trackLength = trackLength;
_trackLengthHalf = trackLength * 0.5f;
}
/// <summary>
/// Sample from a set of possible outcomes with equal probability, i.e. a uniform discrete distribution.
/// </summary>
/// <param name="numberOfOutcomes">The number of possible outcomes.</param>
/// <param name="rng">Random number generator.</param>
/// <returns>An integer between 0..numberOfOutcomes-1.</returns>
public static int SampleUniformDistribution(int numberOfOutcomes, XorShiftRandom rng)
{
return (int)(rng.NextDouble() * numberOfOutcomes);
}
/// <summary>
/// Sample from a binary distribution with the specified probability split between state false and true.
/// </summary>
/// <param name="probability">A probability between 0..1 that describes the probbaility of sampling boolean true.</param>
/// <param name="rng">Random number generator.</param>
public static bool SampleBinaryDistribution(double probability, XorShiftRandom rng)
{
return rng.NextDouble() < probability;
}
/// <summary>
/// Default constructor.
/// </summary>
public TestCaseField()
{
_rng = new XorShiftRandom();
}
/// <summary>
/// Randomly select a function based on each function's selection probability.
/// </summary>
public ActivationFunctionInfo GetRandomFunction(XorShiftRandom rng)
{
return _functionList[DiscreteDistributionUtils.Sample(_rwl, rng)];
}
/// <summary>
/// Rounds up or down to a whole number by using the fractional part of the input value
/// as the probability that the value will be rounded up.
///
/// This is useful if we wish to round values and then sum them without generating a rounding bias.
/// For monetary rounding this problem is solved with rounding to e.g. the nearest even number which
/// then causes a bias towards even numbers.
///
/// This solution is more appropriate for certain types of scientific values.
/// </summary>
public static double ProbabilisticRound(double val, XorShiftRandom rng)
{
double integerPart = Math.Floor(val);
double fractionalPart = val - integerPart;
return rng.NextDouble() < fractionalPart ? integerPart + 1.0 : integerPart;
}
/// <summary>
/// Default constructor.
/// </summary>
public WalkerWorld(XorShiftRandom rng) : this(rng, 300)
{}
/// <summary>
/// For activation functions that accept auxiliary arguments; generates random initial values for aux arguments for newly
/// added nodes (from an 'add neuron' mutation).
/// </summary>
public double[] GetRandomAuxArgs(XorShiftRandom rng, double connectionWeightRange)
{
throw new SharpNeatException("GetRandomAuxArgs() called on activation function that does not use auxiliary arguments.");
}
public void NextLowerUpper_LongRange_Distribution()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
int maxValHalf = int.MaxValue / 2;
int lowerBound = -(maxValHalf + 10000);
int upperBound = (maxValHalf + 10000);
// N.B. double precision can represent every Int32 value exactly.
double[] sampleArr = new double[sampleCount];
for(int i=0; i<sampleCount; i++) {
sampleArr[i] = rng.Next(lowerBound, upperBound);
}
UniformDistributionTest(sampleArr, lowerBound, upperBound);
}
public void NextLowerUpper_LongRange_Bounds()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
Random sysRng = new Random();
int maxValHalf = int.MaxValue / 2;
double[] sampleArr = new double[sampleCount];
for(int i=0; i<sampleCount; i++)
{
int lowerBound = -(maxValHalf + (sysRng.Next()/2));
int upperBound = (maxValHalf + (sysRng.Next()/2));
int sample = rng.Next(lowerBound, upperBound);
if(sample < lowerBound || sample >= upperBound) {
Assert.Fail();
}
}
}
public void NextLowerUpper()
{
int sampleCount = 10000000;
XorShiftRandom rng = new XorShiftRandom();
double[] sampleArr = new double[sampleCount];
for(int i=0; i<sampleCount; i++){
sampleArr[i] = rng.Next(1000000, 1234567);
}
UniformDistributionTest(sampleArr, 1000000, 1234567);
}
public MemoryStreamFuzzer(MemoryStream strmA, MemoryBlockStream strmB, int seed)
{
_strmA = strmA;
_strmB = strmB;
_rng = new XorShiftRandom(seed);
}
/// <summary>
/// Genetic mutation for auxiliary argument data.
/// </summary>
public void MutateAuxArgs(double[] auxArgs, XorShiftRandom rng, ZigguratGaussianSampler gaussianSampler, double connectionWeightRange)
{
throw new SharpNeatException("MutateAuxArgs() called on activation function that does not use auxiliary arguments.");
}
/// <summary>
/// Construct with the provided RNG source.
/// </summary>
public ZigguratGaussianSampler(XorShiftRandom rng)
{
_rng = rng;
// Initialise rectangle position data.
// _x[i] and _y[i] describe the top-right position ox Box i.
// Allocate storage. We add one to the length of _x so that we have an entry at _x[_blockCount], this avoids having
// to do a special case test when sampling from the top box.
_x = new double[__blockCount + 1];
_y = new double[__blockCount];
// Determine top right position of the base rectangle/box (the rectangle with the Gaussian tale attached).
// We call this Box 0 or B0 for short.
// Note. x[0] also describes the right-hand edge of B1. (See diagram).
_x[0] = __R;
_y[0] = GaussianPdfDenorm(__R);
// The next box (B1) has a right hand X edge the same as B0.
// Note. B1's height is the box area divided by its width, hence B1 has a smaller height than B0 because
// B0's total area includes the attached distribution tail.
_x[1] = __R;
_y[1] = _y[0] + (__A / _x[1]);
// Calc positions of all remaining rectangles.
for(int i=2; i<__blockCount; i++)
{
_x[i] = GaussianPdfDenormInv(_y[i-1]);
_y[i] = _y[i-1] + (__A / _x[i]);
}
// For completeness we define the right-hand edge of a notional box 6 as being zero (a box with no area).
_x[__blockCount] = 0.0;
// Useful precomputed values.
_A_Div_Y0 = __A / _y[0];
_xComp = new uint[__blockCount];
// Special case for base box. _xComp[0] stores the area of B0 as a proportion of __R
// (recalling that all segments have area __A, but that the base segment is the combination of B0 and the distribution tail).
// Thus -xComp[0[ is the probability that a sample point is within the box part of the segment.
_xComp[0] = (uint)(((__R * _y[0]) / __A) * (double)uint.MaxValue);
for(int i=1; i<__blockCount-1; i++) {
_xComp[i] = (uint)((_x[i+1] / _x[i]) * (double)uint.MaxValue);
}
_xComp[__blockCount-1] = 0; // Shown for completeness.
// Sanity check. Test that the top edge of the topmost rectangle is at y=1.0.
// Note. We expect there to be a tiny drift away from 1.0 due to the inexactness of floating
// point arithmetic.
Debug.Assert(Math.Abs(1.0 - _y[__blockCount-1]) < 1e-10);
}
