Gnuplot iostream interface

This interface allows gnuplot to be controlled from C++ and is designed to be the lowest hanging fruit. In other words, if you know how gnuplot works it should only take 30 seconds to learn this library. Basically it is just an iostream pipe to gnuplot with some extra functions for pushing data arrays and getting mouse clicks. Data sources include STL containers (eg. vector or map) and one or two dimensional Blitz++ arrays (of scalars or TinyVectors). Support for other data sources should be easy to add.

#include <map>
#include <vector>

#include <math.h>

//#define GNUPLOT_ENABLE_BLITZ
#include "gnuplot-iostream.h"

int main() {
	Gnuplot gp;
	gp << "set terminal png\n";

	std::vector<double> y_pts;
	for(int i=0; i<1000; i++) {
		double y = (i/500.0-1) * (i/500.0-1);
		y_pts.push_back(y);
	}

	gp << "set output 'my_graph_1.png'\n";
	gp << "p '-' w l, sin(x/200) w l\n";
	gp.send(y_pts);
	// Or this:
	//gp.send(y_pts.begin(), y_pts.end());

	// NOTE: we can use map here because the X values are intended to be
	// sorted.  If this was not the case, vector<pair<double,double>> could be
	// used instead.

	std::map<double, double> xy_pts_A;
	for(double x=-2; x<2; x+=0.01) {
		double y = x*x*x;
		xy_pts_A[x] = y;
	}

	std::map<double, double> xy_pts_B;
	for(double alpha=0; alpha<1; alpha+=1.0/24.0) {
		double theta = alpha*2.0*3.14159;
		xy_pts_B[cos(theta)] = sin(theta);
	}

	gp << "set output 'my_graph_2.png'\n";
	gp << "set xrange [-2:2]\nset yrange [-2:2]\n";
	gp << "p '-' w l t 'cubic', '-' w p t 'circle'\n";
	gp.send(xy_pts_A).send(xy_pts_B);
	// Or this:
	//gp.send(xy_pts_A.begin(), xy_pts_A.end());
	//gp.send(xy_pts_B.begin(), xy_pts_B.end());

#ifdef GNUPLOT_ENABLE_BLITZ
	gp << "set output 'my_graph_3.png'\n";
	gp << "set auto x\n";
	gp << "set auto y\n";
	blitz::Array<double, 1> y_arr(100);
	blitz::Array<blitz::TinyVector<double, 2>, 1> xy_arr(100);
	blitz::firstIndex bi;
	y_arr = cos(bi * 0.1);
	xy_arr[0] = cos(bi * 0.1) * 100;
	xy_arr[1] = sin(bi * 0.1);
	gp << "p '-' w l, '-' w l\n";
	gp.send(y_arr);
	gp.send(xy_arr);
#endif // GNUPLOT_ENABLE_BLITZ

	// If this was an interactive session (i.e. not a png terminal),
	// this would get a mouse press:
	//double mx, my;
	//int mb;
	//gp.getMouse(mx, my, mb);
	//printf("You pressed mouse button %d at x=%f y=%f\n", mb, mx, my);
}

Gnuplot iostream interface

Synopsis