/// <summary>
/// Constructs a new Multi-class Kernel Support Vector Machine
/// </summary>
/// <param name="kernel">The chosen kernel for the machine.</param>
/// <param name="inputs">The number of inputs for the machine.</param>
/// <param name="classes">The number of classes in the classification problem.</param>
/// <remarks>
/// If the number of inputs is zero, this means the machine
/// accepts a indefinite number of inputs. This is often the
/// case for kernel vector machines using a sequence kernel.
/// </remarks>
public MulticlassSupportVectorMachine(int inputs, IKernel kernel, int classes)
{
if (classes <= 1)
{
throw new ArgumentException("The machine must have at least two classes.", "classes");
}
// Create the kernel machines
machines = new KernelSupportVectorMachine[classes - 1][];
for (int i = 0; i < classes - 1; i++)
{
machines[i] = new KernelSupportVectorMachine[i + 1];
for (int j = 0; j <= i; j++)
{
machines[i][j] = new KernelSupportVectorMachine(kernel, inputs);
}
}
}
/// <summary>
/// Computes the given input to produce the corresponding output.
/// </summary>
/// <param name="inputs">An input vector.</param>
/// <param name="votes">A vector containing the number of votes for each class.</param>
/// <returns>The output for the given input.</returns>
public int Compute(double[] inputs, out int[] votes)
{
// out variables cannot be passed into delegates,
// so will be creating a copy for the vote array.
int[] voting = new int[this.Classes];
// For each class
GABIZ.Base.Parallel.For(0, Classes, i =>
{
// For each other class
for (int j = 0; j < i; j++)
{
KernelSupportVectorMachine machine = this[i, j];
double answer = machine.Compute(inputs);
// Compute the two-class problem
if (answer < 0)
{
voting[i] += 1; // Class i has won
}
else
{
voting[j] += 1; // Class j has won
}
}
});
// Voting finished.
votes = voting;
// Select class which maximum number of votes
int output; Matrix.Max(votes, out output);
return(output); // Return as the output.
}
public static KernelSupportVectorMachine stringToSVM(string s)
{
string[] sP = s.Split('~');
int inputs = Convert.ToInt32(sP[0]); //Read inputs
int l = Convert.ToInt32(sP[1]); //Read number of support vectors
string[] temp = sP[2].Split(' '); //Read first support vector
int n = temp.Length;
double[,] supportVectors = new double[l, n];
for (int i = 0; i < n; i++)
{
supportVectors[0, i] = Convert.ToDouble(temp[i]);
}
for (int i = 1; i < l; i++)
{
temp = sP[2 + i].Split(' ');
for (int j = 0; j < n; j++)
{
supportVectors[i, j] = Convert.ToDouble(temp[j]);
}
}
double threshold = Convert.ToDouble(sP[2 + l]);
string[] _weights = sP[3 + l].Split(' '); //Read weight;
int wL = _weights.Length;
double[] weights = new double[wL];
for (int i = 0; i < wL; i++)
{
weights[i] = Convert.ToDouble(_weights[i]);
}
IKernel kernel = new Polynomial(2, 1);
string kernelString = sP[4 + l];
switch (kernelString)
{
case "Gaussian": kernel = new Statistics.Kernels.Gaussian(Convert.ToDouble(sP[5 + l]));
break;
case "Polynomial": kernel = new Polynomial(Convert.ToInt32(sP[5 + l]), Convert.ToDouble(sP[6 + l]));
break;
case "Linear": kernel = new Linear(Convert.ToDouble(sP[5 + l]));
break;
case "Sigmoid": kernel = new Sigmoid(Convert.ToDouble(sP[5 + l]), Convert.ToDouble(sP[6 + l]));
break;
}
KernelSupportVectorMachine svm = new KernelSupportVectorMachine(kernel, inputs);
svm.SupportVectors = supportVectors.ToArray();
svm.Threshold = threshold;
svm.Weights = weights;
return(svm);
}
public static string svmToString(KernelSupportVectorMachine svm)
{
if (svm == null)
{
return(null);
}
string s = "";
string temp = "";
s += svm.Inputs + "~"; //Write input
int l = svm.SupportVectors.Length;
s += l + "~"; //Length of support vectors
for (int i = 0; i < l; i++)
{
int n = svm.SupportVectors[i].Length;
temp = "";
for (int j = 0; j < n; j++)
{
temp += svm.SupportVectors[i][j] + " ";
}
temp = temp.Trim();
s += temp + "~";
}
s += svm.Threshold + "~";
l = svm.Weights.Length;
temp = "";
for (int i = 0; i < l; i++)
{
temp += svm.Weights[i] + " ";
}
temp = temp.Trim();
s += temp + "~";
string[] _kType = svm.Kernel.ToString().Split('.');
int u = _kType.Length;
string kType = _kType[u - 1];
switch (kType)
{
case "Gaussian": Statistics.Kernels.Gaussian gKernel = svm.Kernel as Statistics.Kernels.Gaussian;
s += "Gaussian" + "~";
s += gKernel.Sigma;
break;
case "Polynomial": Polynomial pKernel = svm.Kernel as Polynomial;
s += "Polynomial" + "~";
s += pKernel.Degree + "~";
s += pKernel.Constant;
break;
case "Linear": Linear lKernel = svm.Kernel as Linear;
s += "Linear" + "~";
s += lKernel.Constant;
break;
case "Sigmoid": Sigmoid sKernel = svm.Kernel as Sigmoid;
s += "Sigmoid" + "~";
s += sKernel.Gamma + "~";
s += sKernel.Gamma;
break;
}
return(s);
}
