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x21.cc

//---------------------------------------------------------------------------//
// $Id: x21.cc,v 1.7 2004/03/04 09:20:45 andrewross Exp $
//---------------------------------------------------------------------------//
//
//---------------------------------------------------------------------------//
// Copyright (C) 2004  Andrew Ross <andrewr@coriolis.greenend.org.uk>
// Copyright (C) 2004  Alan W. Irwin
//
// This file is part of PLplot.
//
// PLplot is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; version 2 of the License.
//
// PLplot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with PLplot; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
//---------------------------------------------------------------------------//
//
//---------------------------------------------------------------------------//
// Implementation of PLplot example 21 in C++.
//---------------------------------------------------------------------------//

#include "plstream.h"

#include <iostream>
#include <cmath>
#include <time.h>

#if !defined(HAVE_ISNAN)
  #define isnan(x) ((x) != (x))
#endif

// Need for some Mac OSX systems with broken <cmath> header
#ifdef BROKEN_ISNAN_CXX
extern "C" int isnan (double);
#endif

#ifdef USE_NAMESPACE
using namespace std;
#endif

class x21 {

public:
  x21(int, char **);

private:
  void create_data(PLFLT **xi, PLFLT **yi, PLFLT **zi, int pts);
  void free_data(PLFLT *x, PLFLT *y, PLFLT *z);
  void create_grid(PLFLT **xi, int px, PLFLT **yi, int py);
  void free_grid(PLFLT *x, PLFLT *y);
  void cmap1_init();

  PLFLT MIN(PLFLT x, PLFLT y) { return (x<y?x:y);};
  PLFLT MAX(PLFLT x, PLFLT y) { return (x>y?x:y);};

private:
  // Class data
  plstream *pls;

  PLFLT xm, xM, ym, yM;

  // Options data structure definition.
  static PLINT pts;
  static PLINT xp;
  static PLINT yp;
  static PLINT nl;
  static int knn_order;
  static PLFLT threshold;
  static PLFLT wmin;
  static int randn;
  static int rosen;
  static PLOptionTable options[];
};


int x21::pts = 500;
int x21::xp = 25;
int x21::yp = 20;
int x21::nl = 15;
int x21::knn_order = 20;
PLFLT x21::threshold = 1.001;
PLFLT x21::wmin = -1e3;
int x21::randn = 0;
int x21::rosen = 0;

PLOptionTable x21::options[] = {
  {
    "npts",
    NULL,
    NULL,
    &pts,
    PL_OPT_INT,
    "-npts points",
    "Specify number of random points to generate [500]" },
  {
    "randn",
    NULL,
    NULL,
    &randn,
    PL_OPT_BOOL,
    "-randn",
    "Normal instead of uniform sampling -- the effective \n\
\t\t\t  number of points will be smaller than the specified." },
  {
    "rosen",
    NULL,
    NULL,
    &rosen,
    PL_OPT_BOOL,
    "-rosen",
    "Generate points from the Rosenbrock function."},
  {
    "nx",
    NULL,
    NULL,
    &xp,
    PL_OPT_INT,
    "-nx points",
    "Specify grid x dimension [25]" },
  {
    "ny",
    NULL,
    NULL,
    &yp,
    PL_OPT_INT,
    "-ny points",
    "Specify grid y dimension [20]" },
  {
    "nlevel",
    NULL,
    NULL,
    &nl,
    PL_OPT_INT,
    "-nlevel ",
    "Specify number of contour levels [15]" },
  {
    "knn_order",
    NULL,
    NULL,
    &knn_order,
    PL_OPT_INT,
    "-knn_order order",
    "Specify the number of neighbors [20]" },
  {
    "threshold",
    NULL,
    NULL,
    &threshold,
    PL_OPT_FLOAT,
    "-threshold float",
    "Specify what a thin triangle is [1. < [1.001] < 2.]" },

  {
    NULL,                       /* option */
    NULL,                       /* handler */
    NULL,                       /* client data */
    NULL,                       /* address of variable to set */
    0,                          /* mode flag */
    NULL,                       /* short syntax */
    NULL }                      /* long syntax */
};

x21::x21( int argc, char ** argv ) {
  PLFLT *x, *y, *z, *clev;
  PLFLT *xg, *yg, **zg, **szg;
  PLFLT zmin, zmax, lzm, lzM;
  long ct;
  int i, j, k;
  PLINT alg;
  char ylab[40], xlab[40];
  char *title[] = {"Cubic Spline Approximation",
               "Delaunay Linear Interpolation",
               "Natural Neighbors Interpolation",
               "KNN Inv. Distance Weighted",
               "3NN Linear Interpolation",
               "4NN Around Inv. Dist. Weighted"};

  PLFLT opt[] = {0., 0., 0., 0., 0., 0.};

  xm = ym = -0.2;
  xM = yM = 0.8;

  // plplot initialization

  pls = new plstream();

  // Parse and process command line arguments.
  pls->MergeOpts(options, "x21c options", NULL);
  pls->ParseOpts( &argc, argv, PL_PARSE_FULL );

  opt[2] = wmin;
  opt[3] = (PLFLT) knn_order;
  opt[4] = threshold;

  // Initialize PLplot.
  pls->init();

  create_data(&x, &y, &z, pts); /* the sampled data */
  zmin = z[0];
  zmax = z[0];
  for (i=1; i<pts; i++) {
    if (z[i] > zmax)
      zmax = z[i];
    if (z[i] < zmin)
      zmin = z[i];
  }

  create_grid(&xg, xp, &yg, yp); /* grid the data at */
  pls->Alloc2dGrid(&zg, xp, yp); /* the output grided data */
  clev = new PLFLT[nl];

  sprintf(xlab, "Npts=%d gridx=%d gridy=%d", pts, xp, yp);
  pls->col0(1);
  pls->env(xm, xM, ym, yM, 2, 0);
  pls->col0(15);
  pls->lab(xlab, "", "The original data");
  pls->col0(2);
  pls->poin(pts, x, y, 5);
  pls->adv(0);

  pls->ssub(3,2);

  for (k=0; k<2; k++) {
    pls->adv(0);
    for (alg=1; alg<7; alg++) {

      ct = clock();
      pls->griddata(x, y, z, pts, xg, xp, yg, yp, zg, alg, opt[alg-1]);
      sprintf(xlab, "time=%d ms", (clock() - ct)/1000);
      sprintf(ylab, "opt=%.3f", opt[alg-1]);

      /* - CSA can generate NaNs (only interpolates?!).
       * - DTLI and NNI can generate NaNs for points outside the convex hull
       *      of the data points.
       * - NNLI can generate NaNs if a sufficiently thick triangle is not found
       *
       * PLplot should be NaN/Inf aware, but changing it now is quite a job...
       * so, instead of not plotting the NaN regions, a weighted average over
       * the neighbors is done.
       */

      if (alg == GRID_CSA || alg == GRID_DTLI || alg == GRID_NNLI || alg == GRID_NNI) {
      int ii, jj;
      PLFLT dist, d;

      for (i=0; i<xp; i++) {
        for (j=0; j<yp; j++) {
          if (isnan(zg[i][j])) { /* average (IDW) over the 8 neighbors */

            zg[i][j] = 0.; dist = 0.;

            for (ii=i-1; ii<=i+1 && ii<xp; ii++) {
            for (jj=j-1; jj<=j+1 && jj<yp; jj++) {
              if (ii >= 0 && jj >= 0 && !isnan(zg[ii][jj])) {
                d = (abs(ii-i) + abs(jj-j)) == 1 ? 1. : 1.4142;
                zg[i][j] += zg[ii][jj]/(d*d);
                dist += d;
              }
            }
            }
            if (dist != 0.)
            zg[i][j] /= dist;
            else
            zg[i][j] = zmin;

          }
        }
      }
      }

      pls->MinMax2dGrid(zg, xp, yp, &lzM, &lzm);

      pls->col0(1);
      pls->adv(alg);

      if (k == 0) {

      lzm = MIN(lzm, zmin);
      lzM = MAX(lzM, zmax);
      for (i=0; i<nl; i++)
        clev[i] = lzm + (lzM-lzm)/(nl-1)*i;

      pls->env0(xm, xM, ym, yM, 2, 0);
      pls->col0(15);
      pls->lab(xlab, ylab, title[alg-1]);
      pls->shades(zg, xp, yp, NULL, xm, xM, ym, yM,
             clev, nl, 1, 0, 1, plfill, 1, NULL, NULL);
      pls->col0(2);
      } else {

      for (i=0; i<nl; i++)
        clev[i] = lzm + (lzM-lzm)/(nl-1)*i;

      cmap1_init();
      pls->vpor(0.0, 1.0, 0.0, 0.9);
      pls->wind(-1.0, 1.0, -1.0, 1.5);
      /*
       * For the comparition to be fair, all plots should have the
       * same z values, but to get the max/min of the data generated
       * by all algorithms would imply two passes. Keep it simple.
       *
       * plw3d(1., 1., 1., xm, xM, ym, yM, zmin, zmax, 30, -60);
       */

      pls->w3d(1., 1., 1., xm, xM, ym, yM, lzm, lzM, 30, -60);
      pls->box3("bnstu", ylab, 0.0, 0,
             "bnstu", xlab, 0.0, 0,
             "bcdmnstuv", "", 0.0, 4);
      pls->col0(15);
      pls->lab("", "", title[alg-1]);
      pls->plot3dc(xg, yg, zg, xp, yp, DRAW_LINEXY | MAG_COLOR | BASE_CONT, clev, nl);
      }
    }
  }

  free_data(x, y, z);
  free_grid(xg, yg);
  delete[] clev;
  pls->Free2dGrid(zg, xp, yp);

  delete pls;


}

void x21::cmap1_init() {

  PLFLT i[2], h[2], l[2], s[2];

  i[0] = 0.0;           /* left boundary */
  i[1] = 1.0;           /* right boundary */

  h[0] = 240; /* blue -> green -> yellow -> */
  h[1] = 0;   /* -> red */

  l[0] = 0.6;
  l[1] = 0.6;

  s[0] = 0.8;
  s[1] = 0.8;

  pls->scmap1n(256);
  pls->scmap1l(0, 2, i, h, l, s, NULL);
}

void x21::create_grid(PLFLT **xi, int px, PLFLT **yi, int py) {

  PLFLT *x, *y;
  int i;

  x = *xi = new PLFLT[px];
  y = *yi = new PLFLT[py];

  for (i=0; i<px; i++)
    *x++ = xm + (xM-xm)*i/(px-1.);

  for (i=0; i<py; i++)
    *y++ = ym + (yM-ym)*i/(py-1.);
}

void x21::free_grid(PLFLT *xi, PLFLT *yi) {
  delete[] xi;
  delete[] yi;
}

void x21::create_data(PLFLT **xi, PLFLT **yi, PLFLT **zi, int pts) {
  int i;
  PLFLT *x, *y, *z, r;
  PLFLT xt, yt;

  *xi = x = new PLFLT[pts];
  *yi = y = new PLFLT[pts];
  *zi = z = new PLFLT[pts];

  for(i=0; i<pts; i++) {
    xt = drand48();
    yt = drand48();
    if (!randn) {
      *x = xt + xm;
      *y = yt + ym;
    } else { /* std=1, meaning that many points are outside the plot range */
      *x = sqrt(-2.*log(xt)) * cos(2.*M_PI*yt) + xm;
      *y = sqrt(-2.*log(xt)) * sin(2.*M_PI*yt) + ym;
    }
    if (!rosen) {
      r = sqrt((*x) * (*x) + (*y) * (*y));
      *z = exp(-r * r) * cos(2.0 * M_PI * r);
    } else {
      *z = log(pow(1. - *x, 2.) + 100. * pow(*y - pow(*x, 2.), 2.));
    }
    x++; y++; z++;
  }
}

void x21::free_data(PLFLT *x, PLFLT *y, PLFLT *z) {
  delete[] x;
  delete[] y;
  delete[] z;
}

int main( int argc, char ** argv ) {
  x21 *x = new x21( argc, argv );

  delete x;
}


//---------------------------------------------------------------------------//
//                              End of x21.cc
//---------------------------------------------------------------------------//



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