private calculatedPoint findMostDistantPoint(double[][] allPoints, double[] refPoint)
{
calculatedPoint mostDistantPoint = new calculatedPoint();
mostDistantPoint.pointValue = new double[refPoint.Length];
mostDistantPoint.pointID = 0;
double maxDist = 0;
//from ref point find the most distant point
for (int i = 0; i < allPoints.Length; i++)
{
double d = 0;
for (int j = 0; j < allPoints[i].Length; j++)
d += (refPoint[j] - allPoints[i][j]) * (refPoint[j] - allPoints[i][j]);
d = Math.Sqrt(d);
if (d > maxDist)
{
maxDist = d;
mostDistantPoint.pointValue = allPoints[i];
mostDistantPoint.pointID = i;
}
}
return mostDistantPoint;
}
private calculatedPoint findMostDistantPointFromMult(double[][] allPoints, double[][] refPoints)
{
calculatedPoint mostDistantPoint = new calculatedPoint();
mostDistantPoint.pointValue = new double[refPoints[0].Length];
mostDistantPoint.pointID = 0;
double maxDist = 0;
bool isTheSamePoint = false;
//from ref point find the most distant point
for (int i = 0; i < allPoints.Length; i++)
{
double sumPointDist = 0;
// check to not compare with point that has already been used
isTheSamePoint = false;
for (int j = 0; j < refPoints.Length; j++)
if (allPoints[i] == refPoints[j]) isTheSamePoint = true;
if (!isTheSamePoint)
{
for (int j = 0; j < refPoints.Length; j++)
{
if (allPoints[i] != refPoints[j])
{
double d = 0;
for (int k = 0; k < refPoints[j].Length; k++)
d += (refPoints[j][k] - allPoints[i][k]) * (refPoints[j][k] - allPoints[i][k]);
d = Math.Sqrt(d);
sumPointDist = d;
}
}
if (sumPointDist > maxDist)
{
maxDist = sumPointDist;
mostDistantPoint.pointValue = allPoints[i];
mostDistantPoint.pointID = i;
}
}
}
return mostDistantPoint;
}
private double[][] SIVM_algorithm(double[][] points)
{
//number of points for the volume is 2^number of dimensions. i.e: 2D = square, 3D = cube, 4D = no idea how its called!
int dimensions = System.Convert.ToInt16(points[0].Length);
int numberOfPoints = System.Convert.ToInt16(Math.Pow(2, dimensions));
double[][] volumePoints = new double[numberOfPoints][];
double[] volumePointsID = new double[numberOfPoints];
//normalize data
double[][] normalizedData = normalizeData(points);
//find a random P1 point in the sample
Random rnd = new Random();
double[] P1 = normalizedData[rnd.Next(0, normalizedData.Length)];
//from P1, find the most distant point -> P2
calculatedPoint P2 = findMostDistantPoint(normalizedData, P1);
//from P2, find the most distant point -> P3 (first volume coordinate)
volumePoints[0] = new double[dimensions];
calculatedPoint P3 = findMostDistantPoint(normalizedData, P2.pointValue);
volumePoints[0] = P3.pointValue;
volumePointsID[0] = P3.pointID;
//from P3, find the most distant point -> P4 (second volume coordinate)
volumePoints[1] = new double[dimensions];
calculatedPoint P4 = findMostDistantPoint(normalizedData, P3.pointValue);
volumePoints[1] = P4.pointValue;
volumePointsID[1] = P4.pointID;
//Calculate the most distant point from all points
for(int i = 2; i < numberOfPoints; i++) //two first points are already allocated
{
calculatedPoint PI = new calculatedPoint();
volumePoints[i] = new double[dimensions];
double[][] currentPoints = new double[i][];
for(int j = 0; j < i; j++)
{
currentPoints[j] = new double[dimensions];
currentPoints[j] = volumePoints[j];
}
PI = findMostDistantPointFromMult(normalizedData, currentPoints);
volumePoints[i] = PI.pointValue;
volumePointsID[i] = PI.pointID;
}
//the calculation was made with normalized data, now we need to get the ids and save the actual points values
double[][] nonNormalizedVolPoints = new double[numberOfPoints][];
for (int i = 0; i < points.Length; i++)
{
for(int k = 0; k < volumePointsID.Length; k++)
{
if(i == volumePointsID[k])
nonNormalizedVolPoints[k] = points[i];
}
}
return nonNormalizedVolPoints;
}
