gnugraph.cpp

Go to the documentation of this file.

/*
ROBOOP -- A robotics object oriented package in C++
Copyright (C) 1996-2004  Richard Gourdeau

This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.

This library 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


Report problems and direct all questions to:

Richard Gourdeau
Professeur Agrege
Departement de genie electrique
Ecole Polytechnique de Montreal
C.P. 6079, Succ. Centre-Ville
Montreal, Quebec, H3C 3A7

email: richard.gourdeau@polymtl.ca

-------------------------------------------------------------------------------
Revision_history:

2003/02/03: Etienne Lachance
   -Added functions set_plot2d and classe IO_matrix_file.

2003/29/04: Etienne Lachance
   -Class definitions, functions prototype, ... now in gnugraph.h
   -Improved class IO_matrix_file.
   -Class Plot2d, GNUcurve are now using STL string instead of char*.
   -Added class Plot_graph, to create a graph from a data file.
   -Replaced all NULL by 0.
   -Use mkstemp instead of tmpnam in void Plot2d::gnuplot(void).

2003/15/08: Etienne Lachance
   -The member function IO_matrix_file::write writes data in column of each 
    variables, instead of only one. This way it is possible to load a dat file
    in Matlab.

2004/07/01: Etienne Lachance
   -Added doxygen documentation.

2004/07/01: Ethan Tira-Thompson
    -Added support for newmat's use_namespace #define, using ROBOOP namespace

2004/08/10: Etienne Lachance
    -Added class Plot3d.
    -Removed using ROBOOP namespace

2005/08/06 : Richard Gourdeau
    -fixed catch(bad_alloc)

2005/08/06 : Carmine Lia
    -added defined(__MINGW32__) for temp files
-------------------------------------------------------------------------------
*/

static const char rcsid[] = "$Id: gnugraph.cpp,v 1.44 2006/05/19 17:49:58 gourdeau Exp $";

#include "gnugraph.h"

using namespace std;


const char *curvetype[] =
   {"lines",
    "points",
    "linespoints",
    "impulses",
    "dots",
    "steps",
    "boxes"};


GNUcurve::GNUcurve(void)
{
   enLineType = LINES;
}


GNUcurve::GNUcurve(const std::vector<double> & x, std::vector<double> & y,
                   const string & label, LineType_en enLineType_) :
    vdX(x),
    vdY(y),
    clabel(label),
    enLineType(enLineType_)
{
    if (vdX.size() != vdY.size())
    {
        cerr << "GNUcurve::GNUcurve number of x and y elements does not match." << endl;
    }
}

void GNUcurve::dump(void)
{
    cout << "Curve label: " << clabel << endl;
    cout << "Curve type:  " << curvetype[enLineType] << endl;
    cout << "Curve data points: \n";

    unsigned int vSize = vdX.size();
    for(unsigned int i = 0; i < vSize; ++i)
    {
        cout << vdX[i] << " " << vdY[i] << endl;
    }
    cout << endl;
}


Plot2d::Plot2d(void)
{
}

void Plot2d::gnuplot(void)
{
   unsigned int i;
   int strl;
#if defined(__BCPLUSPLUS__) || defined(_MSC_VER) || defined(__WATCOMC__) || defined(__MINGW32__)
   char filename[L_tmpnam];
#else
   char filename[] = "tmpfileXXXXXX";
#endif
   char * filedata=0;
   char * wibsl;
   char bsl = '\\';

#if defined(__BCPLUSPLUS__) || defined(_MSC_VER) || defined(__WATCOMC__) || defined(__MINGW32__)
   tmpnam(filename); /* generate a temporary file name */
#else
   int fd = mkstemp(filename);
   if (fd == -1)
   {
     std::cerr << "mkstemp(" << filename << "failed: " << std::strerror(errno) << std::endl;
     return;
   }
#endif
   /* replacing \ by / */
   while((wibsl = strchr(filename,bsl)) != 0) {
      wibsl[0] = '/';
   }

   {
      ofstream fileout(filename); /* write the command file */
      fileout << gnucommand.c_str();
      fileout << "set title \"" << title << "\"\n";
      fileout << "set xlabel \"" << xlabel << "\"\n";
      fileout << "set ylabel \"" << ylabel << "\"\n";
      fileout << "plot \\\n";

      for(i = 0; i < vCurves.size(); i++) {
         fileout << "\"" << filename << "." << i << "\" ";
         fileout << "title \"" << vCurves[i]->clabel << "\" ";
         fileout << "with " << curvetype[vCurves[i]->enLineType] << " ";
         if( i+1 < vCurves.size()){
            fileout << ", \\\n";
         }
      }
      fileout << "\n";
   }
   try
   {
      filedata = new char[strlen(filename)+3];
   }
   catch(bad_alloc & e)
   {
      cerr << "Plot2d::gnuplot:: new ran out of memory" << endl;
   }
   strcpy(filedata,filename);
   strcat(filedata,".");
   strl = strlen(filedata);

   for(i = 0; i < vCurves.size(); i++)  /* write the data files */
   {
      sprintf(&filedata[strl],"%d",i);
      ofstream fileout(filedata);

//#ifndef _MSC_VER // MSVC++ chokes on the next line !
       // fileout << curves[i].xy;
//#else
      unsigned int vSize = vCurves[i]->vdX.size();
      for (unsigned int j = 0; j < vSize; ++j)
      {
         fileout << vCurves[i]->vdX[j] << " " << vCurves[i]->vdY[j] << endl;
      }

/*
        for(int j = 1; j <= curves[i].xy.Nrows(); j++) {
            for(int k = 1; k <= curves[i].xy.Ncols(); k++) {
                fileout << curves[i].xy(j,k) << " ";
            }
            fileout << "\n";
        }
*/
//#endif
   }
   /* all command and data files are ready for the call to gnuplot */
#if defined(__WIN32__) || defined(_WIN32) || defined(__NT__) || defined(__CYGWIN__) || defined(__MINGW32__)
   /* Windows 95/98/NT/2000 etc */
   char c[L_tmpnam+15];
   char *d;
   HWND hwndm, hwnd;
   if (WinExec(GNUPLOT, SW_SHOWNORMAL) <= 32) { /* start gnuplot */
      /* failed */
      cout << "Cannot find the gnuplot application\n";
      cout << "Press Enter to continue" << endl;
      getchar();
      remove(filename); /* clean up the files and return */
      for(i = 0; i < vCurves.size(); i++) {
         sprintf(&filedata[strl],"%d",i);
         remove(filedata);
      }
      delete filedata;
      return;
   } else { /* succeed */
      /* get gnuplot main window handle */
      hwndm = FindWindow((LPSTR) 0, (LPSTR) "gnuplot");
   }
   hwnd= GetWindow(hwndm, GW_CHILD); /* get gnuplot command area handle */
   if(hwnd == 0) cout << "OUPS!!!\n"; /* something wrong happened */
   sprintf(c,"load \"%s\" \n",filename); /* load command for the plot */

   d = c;
   while(*d != '\0') { /* sending the command through windows messages */
      SendMessage(hwnd,WM_CHAR,*d,1L);
      d++;
   }
   cout << "Press Enter to continue..." << endl;
   getchar();
#else      /*  using a pipe under Unix */
   FILE *command;

   command = popen(GNUPLOT,"w");
   fprintf(command,"load \"%s\"\n",filename); fflush(command);
   fprintf(stderr,"Press Enter to continue...\n"); fflush(stderr);
   getchar();
   pclose(command);
#endif


  remove(filename);
  for(i = 0; i < vCurves.size(); i++) {
    sprintf(&filedata[strl],"%d",i);
    remove(filedata);
  }
  delete filedata;
}


void Plot2d::addcurve(const Matrix & data, const string & label, LineType_en enLineType)
{
    vector<double> x;
    vector<double> y;

    for(int j = 1; j <= data.Nrows(); j++) 
    {
        x.push_back(data(j,1));
        y.push_back(data(j,2));
    }

    try
    {
        GNUcurve *pCurve = new GNUcurve(x, y, label, enLineType);
        vCurves.push_back(PSHR_Curve(pCurve));
    }
    catch (bad_alloc & e)
    {
    }
}

void Plot2d::addcommand(const string & gcom)
{
   gnucommand += gcom;
}

void Plot2d::settitle(const string & t)
{
   title = t;
}

void Plot2d::setxlabel(const string & t)
{
   xlabel = t;
}

void Plot2d::setylabel(const string & t)
{
   ylabel = t;
}

void Plot2d::dump(void)
{
   cout << "gnuplot commands:\n" << gnucommand.c_str();
   cout << "Plot title: " << title.c_str() << "\n";
   cout << "X label:    " << xlabel.c_str() << "\n";
   cout << "Y label:    " << ylabel.c_str() << "\n";

   for (unsigned int i = 0; i < vCurves.size(); ++i) 
    {
      cout << "\nCurve #" << i << "\n";
      vCurves[i]->dump();
   }
}


void Plot3d::gnuplot(const Matrix & xyz)
{
    if (xyz.Ncols() != 3*xyz.Nrows())
    {
        cerr << "Plot3d::gnuplot: wrong size of xyz data matrix." << endl;
        return;
    }

   int strl;
#if defined(__BCPLUSPLUS__) || defined(_MSC_VER) || defined(__WATCOMC__) || defined(__MINGW32__)
   char filename[L_tmpnam];
#else
   char filename[] = "tmpfileXXXXXX";
#endif
   char * filedata=0;
   char * wibsl;
   char bsl = '\\';

#if defined(__BCPLUSPLUS__) || defined(_MSC_VER) || defined(__WATCOMC__) || defined(__MINGW32__)
   tmpnam(filename); /* generate a temporary file name */
#else
   int fd = mkstemp(filename);
   if (fd == -1)
   {
     std::cerr << "mkstemp(" << filename << "failed: " << std::strerror(errno) << std::endl;
     return;
   }
#endif

   while((wibsl = strchr(filename,bsl)) != 0) {
      wibsl[0] = '/';
   }
   {
       ofstream fileout(filename); // write the command file 
       fileout << "set title \"" << title << "\"\n";
       fileout << "set xlabel \"" << xlabel << "\"\n";
       fileout << "set ylabel \"" << ylabel << "\"\n";
       fileout << "set zlabel \"" << zlabel << "\"\n";
       fileout << "splot \\\n";   
       fileout << "\"" << filename << "." << 0 << "\" ";
       fileout << "title \"" << "" << "\" ";
       fileout << "with " << "linespoints" << " ";
   }
   
   try
   {
      filedata = new char[strlen(filename)+3];
   }
   catch(bad_alloc & e)
   {
      cerr << "Plot3d::gnuplot:: new ran out of memory" << endl;
   }
   strcpy(filedata,filename);
   strcat(filedata,".");
   strl = strlen(filedata);

   sprintf(&filedata[strl],"%d",0);
   ofstream fileout(filedata);

   for(int j = 0; j < 3*xyz.Nrows(); j+=3)
   {
       fileout << xyz.SubMatrix(1, xyz.Nrows(), j+1, j+3);
       fileout << " " << endl;
   }

#if defined(__WIN32__) || defined(_WIN32) || defined(__NT__) || defined(__CYGWIN__) || defined(__MINGW32__)
   /* Windows 95/98/NT/2000 etc */
   char c[L_tmpnam+15];
   char *d;
   HWND hwndm, hwnd;
   if (WinExec(GNUPLOT, SW_SHOWNORMAL) <= 32) { /* start gnuplot */
      /* failed */
      cout << "Cannot find the gnuplot application\n";
      cout << "Press Enter to continue" << endl;
      getchar();
      remove(filename); /* clean up the files and return */
      remove(filedata);
      delete filedata;
      return;
   } else { /* succeed */
      /* get gnuplot main window handle */
      hwndm = FindWindow((LPSTR) 0, (LPSTR) "gnuplot");
   }
   hwnd= GetWindow(hwndm, GW_CHILD); /* get gnuplot command area handle */
   if(hwnd == 0) cout << "OUPS!!!\n"; /* something wrong happened */
   sprintf(c,"load \"%s\" \n",filename); /* load command for the plot */

#ifdef __GNUG__        /* Cygnus Gnu C++ for win32*/
   char ccygnus[] = "cd \"c:\"\n"; /* this string should reflect
                                      the drive used to mount / 
                                      where /tmp is located */
   d = ccygnus;
   while(*d != '\0') { /* sending the command through windows messages */
      SendMessage(hwnd,WM_CHAR,*d,1L);
      d++;
   }
#endif
   d = c;
   while(*d != '\0') { /* sending the command through windows messages */
      SendMessage(hwnd,WM_CHAR,*d,1L);
      d++;
   }
   cout << "Press Enter to continue..." << endl;
   getchar();
#else      /*  using a pipe under Unix */
   FILE *command;
   command = popen(GNUPLOT,"w");
   fprintf(command,"load \"%s\"\n",filename); fflush(command);
   fprintf(stderr,"Press Enter to continue...\n"); fflush(stderr);
   getchar();
   pclose(command);
#endif

   remove(filename);
   sprintf(&filedata[strl],"%d",0);
   remove(filedata);

   delete filedata;
}

void Plot3d::settitle(const string & t)
{
   title = t;
}

void Plot3d::setxlabel(const string & t)
{
   xlabel = t;
}

void Plot3d::setylabel(const string & t)
{
   ylabel = t;
}

void Plot3d::setzlabel(const string & t)
{
   zlabel = t;
}

// ---------------------------------------------------------------------------------------

IO_matrix_file::IO_matrix_file(const string & filename_)
{
   filename = filename_;
   position_read = 0;
   nb_iterations_write = 0;
   nb_iterations_read = 0;
   nb_element = 0;
}


short IO_matrix_file::write(const vector<Matrix> & data)
{
   vector<string> title;
   string tmp;
   for(unsigned int i = 1; i <= data.size(); i++)
   {
      tmp = "data#";  // Provide a default name
      tmp += i;
      title.push_back(tmp);
   }

   return IO_matrix_file::write(data, title);
}


short IO_matrix_file::write(const vector<Matrix> & data, const vector<string> & title)
{
   /*
   If the file "filename" does not exist yet, created it. The first lines of the file
   contain the following informations (for each line):
      1) the number of iterations.
      2) second line is empty.
      3) the number(n) of matrix/iteration
      4) number of rows and number of columns of Matrix 1.
      5)  "                                         "   i.
      6)  "                                         "   n.
      7)---------------------------------   (end of header file)

   example of header file;
   1120
       
   2
   6 1 titre#1
   6 1 titre#1
   ---------------------------------
   */
   const char *ptr_filename = filename.c_str(); // transform string to *char
   if(data.size())
   {
      if(!nb_iterations_write)
      {
         struct stat buf;
         if(stat(ptr_filename, &buf) )  // File does not exist
         {
            ofstream outvecfile(ptr_filename);
            if(outvecfile)
            {
               outvecfile << "nd_iterations " << nb_iterations_write
               << "        " << endl;
               outvecfile << "nb_vector " << data.size() << endl;
               for(unsigned int i = 0; i < data.size(); i++)
                  outvecfile << "nb_rows " << data[i].Nrows() << "  "
                  << "nb_cols " << data[i].Ncols() <<  "  "
                  << title[i] << endl;
               outvecfile << "---------------------------------\n";
            }
            else
            {
               cerr << "IO_matrix_file::write: can not open file " << filename.c_str() << endl;
               return IO_COULD_NOT_OPEN_FILE;
            }
         }
         else
         {
            ifstream invecfile(ptr_filename, ios::in);
            if(invecfile)
               invecfile >> nb_iterations_write;
         }
      }

      ofstream outvecfile(ptr_filename, ios::in | ios::out);
      if(outvecfile)
      {
         outvecfile.seekp(strlen("nb_iterations ")); // position at start of fileObject
         outvecfile << ++nb_iterations_write << endl;
         outvecfile.seekp(0, std::ios::end); // position at end of fileObject
         for(unsigned int i = 0; i < data.size(); i++)
         {
            for(int j = 1; j <= data[i].Nrows(); j++) {
               for(int k = 1; k <= data[i].Ncols(); k++) {
                  outvecfile << data[i](j,k) << " ";
               }
            }
         }
         outvecfile << endl;
         outvecfile << endl;
      }
      else
      {
         cerr << "IO_matrix_file::write: can not open file " << filename.c_str() << endl;
         return IO_COULD_NOT_OPEN_FILE;
      }
   }
   else
   {
      cerr << "IO_matrix_file::write: vector data is empty" << endl;
      return IO_DATA_EMPTY;
   }

   return 0;
}


short IO_matrix_file::read(vector<Matrix> & data)
{
   vector<string> data_title;
   string tmp;
   for(unsigned int i = 1; i <= data.size(); i++)
   {
      tmp = "data#";  // Provide a default name
      tmp += i;
      data_title.push_back(tmp);
   }

   return IO_matrix_file::read(data, data_title);
}


short IO_matrix_file::read(vector<Matrix> & data, vector<string> & data_title)
{
   /*
   If the file "filename does not exist yet, created it and fill the first line
   with the number of rows and columns for each element of "data".
   ex: 6x1;3x1;3x3;
   This line indidate that data has 3 elements Matrix. The first one has 6 rows and
   1 columns, the second one has 3 rows and 1 columns ...
   */
   static const char *ptr_filename = filename.c_str(); // transform string to *char
   ifstream invecfile(ptr_filename, ios::in);

   if(invecfile)
   {
      if(!position_read)
      {
         string temp;
         int nbcol = 0, nbrow = 0;
         invecfile >> temp >> nb_iterations_read;
         invecfile >> temp >> nb_element;
         Matrix mat_tmp;
         data.clear();
         data_title.clear();
         for(int i = 1; i <= nb_element; i++)
         {
            data.push_back(mat_tmp);
            data_title.push_back(temp);
         }
         for(int j = 0; j < nb_element; j++)
         {
            invecfile >> temp >> nbrow;
            invecfile >> temp >> nbcol;
            getline(invecfile,data_title[j]);
            if( (nbrow != data[j].Nrows()) ||
                  (nbcol != data[j].Ncols()) )
               data[j] = Matrix(nbrow, nbcol);
         }
         invecfile >> temp;  //------------------------
         position_read = invecfile.tellg();
      }

      if(position_read > 0)
      {
         invecfile.seekg(position_read); // position for reading
         for(unsigned int ii = 0; ii < data.size(); ii++)
            for(int jj = 1; jj <= data[ii].Nrows(); jj++)
               for(int kk = 1; kk <= data[ii].Ncols(); kk++)
                  invecfile >> data[ii](jj,kk);

         position_read = invecfile.tellg(); // position for next reading
      }
   }
   else
   {
      cerr << "IO_matrix_file::read, can not open file" << filename.c_str() << endl;
      return IO_COULD_NOT_OPEN_FILE;
   }
   return 0;
}


short IO_matrix_file::read_all(vector<Matrix> & data, vector<string> & data_title)
{
   static const char *ptr_filename = filename.c_str(); // transform string to *char
   ifstream invecfile(ptr_filename, ios::in);

   if(invecfile)
   {
      string temp;
      int nbcol = 0, nbrow = 0;
      invecfile >> temp >> nb_iterations_read;
      invecfile >> temp >> nb_element;

      Matrix mat_tmp;
      data.clear();
      data_title.clear();
      for(int i = 1; i <= nb_element; i++)
      {
         data.push_back(mat_tmp);
         data_title.push_back(" ");
      }

      for(int j = 0; j < nb_element; j++)
      {
         invecfile >> temp >> nbrow;
         invecfile >> temp >> nbcol;
         if(nbcol >1)
            return IO_MISMATCH_SIZE;

         getline(invecfile,data_title[j]);
         if( (nbrow != data[j].Nrows()) ||
               (nbcol != data[j].Ncols()) )
            data[j] = Matrix(nbrow, nbcol*nb_iterations_read);
      }
      invecfile >> temp;  //---------------------------------

      for(int k = 1; k <= nb_iterations_read; k++)
         for(unsigned int ii = 0; ii < data.size(); ii++)
            for(int jj = 1; jj <= data[ii].Nrows(); jj++)
               invecfile >> data[ii](jj,k);
   }
   else
   {
      cerr << "IO_matrix_file::read_all, can not open file " << filename.c_str() << endl;
      return IO_COULD_NOT_OPEN_FILE;
   }
   return 0;
}

// ---------------------------------------------------------------------------------------

Plot_file::Plot_file(const string & filename) : IO_matrix_file(filename), Plot2d()
{
   //clear the buffers in case of error while reading the file
   if(read_all(data_from_file, data_title))
   {
      data_from_file.clear();
      data_title.clear();
      cerr << "Plot_file::Plot_file: problem in reading file " << filename.c_str() << "." << endl;
   }
}


short Plot_file::graph(const string & title_graph, const string & label, const short x,
                       const short y, const short x_start, const short y_start,
                       const short y_end)
{
   if(data_from_file.size())
   {
      if(data_from_file[x].Ncols() != data_from_file[y].Ncols())
      {
         cerr << "Plot_file::graph: number of rows of xdata and ydata does not match" << endl;
         return X_Y_DATA_NO_MATCH;
      }

      settitle(title_graph.c_str());
      setxlabel(data_title[x]);
      setylabel(data_title[y]);

      string legend;
      for(int i = y_start; i <= y_end; i++)
      {
         ostringstream istr;
         istr << label << i-y_start+1;
         legend = istr.str();

         addcurve((data_from_file[x].SubMatrix(x_start,x_start,1,data_from_file[x].Ncols())
                   & data_from_file[y].SubMatrix(i,i,1,data_from_file[y].Ncols())).t(),
                  legend, DATAPOINTS);
      }
      gnuplot();
      return 0;
   }
   else
   {
      cerr << "Plot_file::graph: data file buffer is empty." << endl;
      return PROBLEM_FILE_READING;
   }
}

// ---------------------------------------------------------------------------------------------

short set_plot2d(const char *title_graph, const char *x_axis_title, const char *y_axis_title,
                 const char *label, LineType_en enLineType, const Matrix &xdata, const Matrix &ydata,
                 int start_y, int end_y)
{

   Plot2d plotgraph;
   char *legend=0;
   try
   {
      legend = new char[strlen(label)+1];
   }
   catch(bad_alloc & e)
   {
      cerr << "set_plot2d:: new ran out of memory" << endl;
      return OUT_OF_MEMORY;
   }

   if(xdata.Ncols() != ydata.Ncols())
   {
      cerr << "set_plot2d:: number of rows of xdata and ydata does not match" << endl;
      return X_Y_DATA_NO_MATCH;
   }

   plotgraph.settitle(title_graph);
   plotgraph.setxlabel(x_axis_title);
   plotgraph.setylabel(y_axis_title);

   for(int i = start_y; i <= end_y; i++)
   {
      snprintf(legend, sizeof(legend), "%s%d", label, i-start_y+1);


      plotgraph.addcurve((xdata & ydata.SubMatrix(i,i,1,ydata.Ncols())).t(), legend, enLineType);
   }
   plotgraph.gnuplot();

   delete [] legend;

   return 0;
}

short set_plot2d(const char *title_graph, const char *x_axis_title, const char *y_axis_title,
                 const vector<char *> label, LineType_en enLineType, const Matrix &xdata, 
                 const Matrix &ydata, const vector<int> & data_select)
{
   Plot2d plotgraph;

   plotgraph.settitle(title_graph);
   plotgraph.setxlabel(x_axis_title);
   plotgraph.setylabel(y_axis_title);

   if(xdata.Ncols() != ydata.Ncols())
   {
      cerr << "set_plot2d:: number of rows of xdata and ydata does not match" << endl;
      return X_Y_DATA_NO_MATCH;
   }
   if(data_select.size() != label.size())
   {
      cerr << "set_plot2d:: number of labels does not match" << endl;
      return LABELS_NBR_NO_MATCH;
   }

   for(unsigned int i = 0; i < data_select.size(); i++)
      plotgraph.addcurve((xdata & ydata.SubMatrix(data_select[i],data_select[i],
                          1,ydata.Ncols())).t(), label[i], enLineType);
   plotgraph.gnuplot();

   return 0;
}


short set_plot3d(const Matrix & xyz, const string & title_graph, const string & x_axis_title, 
                 const string & y_axis_title, const string & z_axis_title)
{

   Plot3d plotgraph;

   plotgraph.settitle(title_graph);
   plotgraph.setxlabel(x_axis_title);
   plotgraph.setylabel(y_axis_title);
   plotgraph.setzlabel(z_axis_title);
   plotgraph.gnuplot(xyz);

   return 0;
}