Passing data array to gnuplot via pipe in c, not file

Question

Now I am transferring the gnuplot file through a pipe in c, something like this:

fprintf(gnuplotPipe, "plot \"data-file.dat\" using 1:2\n"); 

Is there a way that I do not need to write data to a file and then transfer it to gnuplot, so, for example, somehow pass an array or stream to gnuplot, so I can skip writing to the process file and then delete the file? Any help would be appreciated.

Answer 1

Of course you can do it. An example of a terminal command that displays two points connected by a line:

 echo "plot \"< echo -e '4 5\n 3 2'\" w lp pt 2" | gnuplot 

If you want to have a postscript, you can add the following:

 echo "set terminal postscript; plot \"< echo -e '4 5\n 3 2'\" w lp pt 2" | gnuplot &> out.ps 

If you are now using system () or popen () (to catch the output stream), the rest should be simple.

Edit: It seems there are some C (++) - Gnuplot interfaces. Check out this website , which gives an excellent overview of C, C ++, Python, and Fortran wrappers. I'm not sure that they are relevant and work with the latest versions of Gnuplot, but if you do not adapt, it should not be so difficult.

Answer 2

Gnuplot understands the file name '-' to indicate upcoming data. So cut and paste from what I'm currently working on:

 FILE *f = popen("gnuplot", "w"); fprintf(f, "set term png; " "set out 'beforeafter.png'\n" "set xlabel 'before'\n" "set ylabel 'after'\n" "plot '-'\n"); //Am using Apophenia in my project, so use its print function to print the data apop_data_print(dataset, .output_pipe=f); //or use fprintf directly for (int i=0; i< data_len; i++) fprintf(f, "%g %g\n", data_x[i], data_y[i]); fclose(f);