plotting again on the last plot using gnuplot-iostream

Question

i am using gnuplot-iostream to plot datapoints.

So, I have two sets. I can successfully plot the first set, but it fails at the second set.

             first_pts = {....};
             second_pts = {....};
             Gnuplot gp2d;
             gp2d << "set xrange [-5:5]\n";
             gp2d << "set yrange [-5:5]\n";
             for ( auto i = 0 ; i < 2 ; i ++ ) {
                 if ( i == 0 )
                   gp2d << "plot '-' with points title 'first'\n";
                   gp2d.send1d(first_pts);
                 else    
                   gp2d << "replot\n";
                   gp2d.send1d(second_pts);
                 }

I deliberatly do not want the data to be plotted in one iteration, because that wont work in my real environment. Replot is ofcourse wrong here, and hence the question - whats the right way?

Answer 1

Ok, I figured it out. Just add another input to gnuplot plot command and gnuplot will wait for the second point before plotting.

         first_pts = {....};
         second_pts = {....};
         Gnuplot gp2d;
         gp2d << "set xrange [-5:5]\n";
         gp2d << "set yrange [-5:5]\n";
         for ( auto i = 0 ; i < 2 ; i ++ ) {
             if ( i == 0 )
               gp2d << "plot '-' with points title 'first', '-' with points title 'second'\n";
               gp2d.send1d(first_pts);
             else    
               //gp2d << "replot\n";
               gp2d.send1d(second_pts);
             }