/// <summary>
/// Defuzzify a membership function using the Bisector method.
/// https://www.mathworks.com/help/fuzzy/examples/defuzzification-methods.html
/// </summary>
/// <param name="mf"></param>
/// <returns></returns>
public static double DefuzzBisect(MemberFunction mf)
{
double areaTotal = 0;
double[] areas = new double[mf.Length];
// Find the area of each segment
for (int i = 0; i < mf.Length - 1; i++)
{
double x1 = mf.Coords[i][0];
double x2 = mf.Coords[i + 1][0];
double y1 = mf.Coords[i][1];
double y2 = mf.Coords[i + 1][1];
areas[i] = 0.5 * (x2 - x1) * (y1 + y2);
areaTotal += areas[i];
}
double halfArea = areaTotal / 2;
double xMin = 0;
double xMax = 0;
double yLast = 0;
double x = 0;
double y = 0;
double m = 0;
// This is our accumulating area
double tmpArea = 0;
for (int i = 0; i < mf.Length - 1; i++)
{
// Get the area of this segment
m = areas[i];
x = xMax = mf.Coords[i][0];
// Add points in until we cross over to the haldway point
if (tmpArea + m <= halfArea)
{
tmpArea += m;
}
// Cut the distance in hald until we are reasonable close to the point we want
else
{
xMin = mf.Coords[i][0];
xMax = mf.Coords[i + 1][0];
yLast = mf.Coords[i][1];
while (halfArea - tmpArea > 0.000001)
{
x = xMin + ((xMax - xMin) / 2);
y = mf.fuzzify(x);
m = Area(new double[2] {
xMin, yLast
}, new double[2] {
x, y
});
if (tmpArea + m > halfArea)
{
xMax = x;
}
else if (tmpArea + m <= halfArea)
{
tmpArea += m;
xMin = x;
}
}
break;
}
}
return(x);
}
public void fuzzifyTest()
{
MemberFunction mf1 = new MemberFunction(new List <double[]>()
{
new double[2] {
1, 0
}, //0
new double[2] {
2, 1
}, //1 <-- horiz
new double[2] {
3, 1
}, //2 <-- Vertical
new double[2] {
3, 2
}, //3 <-- horiz
new double[2] {
4, 2
}, //4
new double[2] {
5, 0
} //5
});
Assert.AreEqual(mf1.fuzzify(0), 0);
Assert.AreEqual(mf1.fuzzify(1), 0);
Assert.AreEqual(mf1.fuzzify(2), 1);
Assert.AreEqual(mf1.fuzzify(3), 1);
Assert.AreEqual(mf1.fuzzify(4), 2);
Assert.AreEqual(mf1.fuzzify(5), 0);
Assert.AreEqual(mf1.fuzzify(0.5), 0);
Assert.AreEqual(mf1.fuzzify(1.5), 0.5);
Assert.AreEqual(mf1.fuzzify(2.5), 1);
Assert.AreEqual(mf1.fuzzify(3.5), 2);
Assert.AreEqual(mf1.fuzzify(4.5), 1);
Assert.AreEqual(mf1.fuzzify(5.5), 0);
Assert.AreEqual(mf1.fuzzify(-100), 0);
Assert.AreEqual(mf1.fuzzify(100), 0);
Assert.AreEqual(mf1.fuzzify(double.PositiveInfinity), 0);
Assert.AreEqual(mf1.fuzzify(double.NegativeInfinity), 0);
}