CreateTwoSpiralsDataSet.h

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#ifndef CREATE_TWO_SPIRALS_DATA_SET_H_
#define CREATE_TWO_SPIRALS_DATA_SET_H_

#include <Eigen/Core>
#include <OpenANN/util/AssertionMacros.h>
#include <OpenANN/Preprocessing.h>

void createTwoSpiralsDataSet(int density, double maxDiameter,
                             Eigen::MatrixXd& Xtr, Eigen::MatrixXd& Ytr,
                             Eigen::MatrixXd& Xte, Eigen::MatrixXd& Yte)
{
  // Number of interior data points per spiral to generate
  const int points = 96 * density;

  Xtr.resize(points + 1, 2);
  Ytr.resize(points + 1, 1);
  Xte.resize(points + 1, 2);
  Yte.resize(points + 1, 1);
  int trIdx = 0;
  int teIdx = 0;

  for(int i = 0; i <= points; i++)
  {
    // Angle is based on the iteration * PI/16, divided by point density
    const double angle = i * M_PI / (16.0 * density);
    // Radius is the maximum radius * the fraction of iterations left
    const double radius = maxDiameter * (104 * density - i) / (104 * density);
    // x and y are based upon cos and sin of the current radius
    const double x = radius * cos(angle);
    const double y = radius * sin(angle);

    if(i == points)
    {
      Xtr.row(trIdx) << x, y;
      Ytr.row(trIdx) << 1.0;
      Xte.row(trIdx) << -x, -y;
      Yte.row(teIdx) << -1.0;
    }
    else if(i % 2 == 0)
    {
      OPENANN_CHECK_WITHIN(trIdx, 0, points);
      Xtr.row(trIdx) << x, y;
      Ytr.row(trIdx) << 1.0;
      Xtr.row(trIdx + 1) << -x, -y;
      Ytr.row(trIdx + 1) << -1.0;
      trIdx += 2;
    }
    else
    {
      OPENANN_CHECK_WITHIN(teIdx, 0, points);
      Xte.row(teIdx) << x, y;
      Yte.row(teIdx) << 1.0;
      Xte.row(teIdx + 1) << -x, -y;
      Yte.row(teIdx + 1) << -1.0;
      teIdx += 2;
    }
  }

  OpenANN::scaleData(Xte, 0.0, 1.0);
  OpenANN::scaleData(Xtr, 0.0, 1.0);
}

#endif // CREATE_TWO_SPIRALS_DATA_SET_H_