// Plot J cost function
private static void PlotJ(Matrix <double> X, Matrix <double> y, Matrix <double> theta)
{
// Grid over which we will calculate J
double[] theta0_vals = MathNet.Numerics.Generate.LinearSpaced(100, -10, 10);
double[] theta1_vals = MathNet.Numerics.Generate.LinearSpaced(100, -1, 4);
// initialize J_vals to a matrix of 0's
int size = theta0_vals.Length * theta1_vals.Length;
double[] sx = new double[size];
double[] sy = new double[size];
double[] sz = new double[size];
// Fill out J_vals
int idx = 0;
for (int i = 0; i < theta0_vals.Length; i++)
{
for (int k = 0; k < theta1_vals.Length; k++)
{
Matrix <double> t = Matrix <double> .Build.Dense(2, 1);
t[0, 0] = theta0_vals[i];
t[1, 0] = theta1_vals[k];
sx[idx] = theta0_vals[i];
sy[idx] = theta1_vals[k];
sz[idx] = ComputeCost(X, y, t);
idx++;
}
}
GnuPlot.HoldOn();
GnuPlot.Set("terminal wxt 1");
GnuPlot.Set("title \"Cost function J\"");
GnuPlot.Set("key bottom right");
GnuPlot.Set("xlabel \"{/Symbol q}_0\"");
GnuPlot.Set("ylabel \"{/Symbol q}_1\"");
// surface plot
GnuPlot.SPlot(sx, sy, sz, "palette title \"J({/Symbol q}_0,{/Symbol q}_1)\"");
// Contour plot
GnuPlot.Set("terminal wxt 2");
GnuPlot.Set("cntrparam levels auto 10", "logscale z", "xr[-10:10]", "yr[-1:4]");
GnuPlot.Unset("key", "label");
GnuPlot.Contour(sx, sy, sz);
GnuPlot.Plot(new double[] { theta[0, 0] }, new double[] { theta[1, 0] }, "pt 2 ps 1 lc rgb \"red\"");
}
private static void PlotBoundary(Matrix <double> x, C_SVC svc)
{
double min = x.Column(0).Min();
double max = x.Column(0).Max();
double[] x0 = MathNet.Numerics.Generate.LinearSpaced(100, min, max);
min = x.Column(1).Min();
max = x.Column(1).Max();
double[] x1 = MathNet.Numerics.Generate.LinearSpaced(100, min, max);
int size = x0.Length * x1.Length;
double[] sx = new double[size];
double[] sy = new double[size];
double[] sz = new double[size];
int idx = 0;
for (int i = 0; i < x0.Length; i++)
{
for (int j = 0; j < x1.Length; j++)
{
sx[idx] = x0[i];
sy[idx] = x1[j];
svm_node n1 = new svm_node();
n1.index = 1;
n1.value = x0[i];
svm_node n2 = new svm_node();
n2.index = 2;
n2.value = x1[j];
double z = svc.Predict(new [] { n1, n2 });
sz[idx] = z;
idx++;
}
}
GnuPlot.Set("cntrparam levels discrete 0.5");
GnuPlot.Contour(sx, sy, sz, "title \"Decision Boundary\"");
}
public void MakeContour(double[] xBound, double[] yBound)
{
int id = x.Count() - 1;
double[] x1plot = new double[id + 1];
double[] x2plot = new double[id + 1];
for (int i = 0; i <= id; i++)
{
x1plot[i] = x[i][0];
x2plot[i] = x[i][1];
}
string xr = "xr[" + xBound[0] + ":" + xBound[1] + "]";
string yr = "yr[" + yBound[0] + ":" + yBound[1] + "]";
GnuPlot.Unset("key"); //hide the key or legend
GnuPlot.HoldOn();
GnuPlot.Set(xr, yr, "cntrparam levels 20", "isosamples 50", xr, yr, "decimalsign locale"); //notice cntrparam levels (# height levels)
GnuPlot.Plot(x1plot, x2plot, "with linespoints linestyle 1");
GnuPlot.Contour(filename, "lc rgb 'blue'");
}
private static void PlotDecisionBoundary(Vector <double> theta)
{
// Grid over which we will calculate J
double[] x1 = MathNet.Numerics.Generate.LinearSpaced(50, -1, 1.5);
double[] x2 = MathNet.Numerics.Generate.LinearSpaced(50, -1, 1.5);
// initialize J_vals to a matrix of 0's
int size = x1.Length * x2.Length;
double[] sx = new double[size];
double[] sy = new double[size];
double[] sz = new double[size];
int idx = 0;
for (int i = 0; i < x1.Length; i++)
{
for (int j = 0; j < x2.Length; j++)
{
sx[idx] = x1[i];
sy[idx] = x2[j];
Vector <double> v1 = Vector <double> .Build.DenseOfArray(new [] { x1[i] });
Vector <double> v2 = Vector <double> .Build.DenseOfArray(new [] { x2[j] });
Matrix <double> X = MapFeature(v1, v2);
Vector <double> z = X * theta;
sz[idx] = z[0];
idx++;
}
}
GnuPlot.Set("cntrparam levels discrete 0");
GnuPlot.Contour(sx, sy, sz, "title \"Decision Boundary\"");
}
