how do you plot graphs in opencv projects?

edit

i tried to understand usage of Plot2d class maybe the code below will be useful for someone who want to try.

#include <opencv2/highgui.hpp>
#include <opencv2/plot.hpp>

using namespace cv;

int main(int argc, char** argv)
{
   // Plot data must be a 1xN or Nx1 matrix.
   // Plot data type must be double (CV_64F) 
    Mat data( 30, 1, CV_64F );
    randu( data, 0, 500 ); // random values

    Mat plot_result;

    Ptr<plot::Plot2d> plot = plot::Plot2d::create(data);
    plot->setPlotBackgroundColor( Scalar( 50, 50, 50 ) );
    plot->setPlotLineColor( Scalar( 50, 50, 255 ) );
    plot->render( plot_result );

    imshow( "plot", plot_result );
    waitKey();

    plot->setPlotLineColor( Scalar( 50, 255, 255 ) );
    data = data / 3;
    plot->render( plot_result );

    imshow( "plot", plot_result );
    waitKey();

    plot->setPlotGridColor( Scalar( 255, 0, 255 ) );
    data = data * 4;
    plot->render( plot_result );

    imshow( "plot", plot_result );
    waitKey();

    plot->setPlotTextColor( Scalar( 255, 0, 0 ) );
    randu( data, 100, 400 );
    plot->render( plot_result );

    imshow( "plot", plot_result );
    waitKey();

    return 0;
}

sample java code

import org.opencv.core.Core;
import org.opencv.core.Scalar;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.imgcodecs.Imgcodecs;
import org.opencv.plot.Plot2d;
public class test
{
   public static void main( String[] args )
   {
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      Mat data = new Mat(1, 20, CvType.CV_64F);
      Core.randu(data, 1, 10);
      Plot2d plot = Plot2d.create(data);
      Mat mplot = new Mat();
      plot.setPlotLineColor(new Scalar(0,0,255));
      plot.render(mplot);
      Imgcodecs.imwrite("e:/test.png", mplot);
   }
}

Try this cvplot framework. You can plot in real time and and have multiple plots in a single window.

You could try Profactor CvPlot https://github.com/Profactor/cv-plot. (I am the developer). It is very easy to integrate, purely opencv based and can be extended with custom drawables. This is how you can plot to a cv::Mat or show a diagram with an interactive viewer:

#include <CvPlot/cvplot.h>
std::vector<double> x(20*1000), y1(x.size()), y2(x.size()), y3(x.size());
for (size_t i = 0; i < x.size(); i++) {
    x[i] = i * CV_2PI / x.size();
    y1[i] = std::sin(x[i]);
    y2[i] = y1[i] * std::sin(x[i]*50);
    y3[i] = y2[i] * std::sin(x[i]*500);
}
auto axes = CvPlot::makePlotAxes();
axes.create<CvPlot::Series>(x, y3, "-g");
axes.create<CvPlot::Series>(x, y2, "-b");
axes.create<CvPlot::Series>(x, y1, "-r");

//plot to a cv::Mat
cv::Mat mat = axes.render(300, 400);

//or show with interactive viewer
CvPlot::show("mywindow", axes);

You may also want to try Leonardvandriel's cvplot. It works similar but cannot be extended with custom drawables.