Pass argument to GNUPLOT config file

Question

Here is my gnuplot config file :

reset
set terminal png
set output "rp.png"
set title textcolor rgb "red" "R/P"
set yrange[0:110]
set xrange[0:110]
set xlabel "Rappel"
set ylabel "Précision"
set style data points
plot "test.dat" using 2:1 with linespoints

I would like to be able to replace at the last line "test.dat" by something like "filename" where "filename" would be passed.

For the moment I am just making this

FILE *gp;
 if(WIN32)
 {
   cout<<"Win 32"<<endl;
   
   gp=_popen("gnuplot", "w");
 }
 else
 {
   cout<<"pas win 32"<<endl;
   gp=popen("gnuplot", "w");
 }
 if(gp == NULL)
 {
   fprintf(stderr, "Oops, I can't find %s.");
   //exit(EXIT_FAILURE);
 }
 fprintf(gp, "load \"config\"\n");
 fflush(gp); 
 pclose(gp);

but I have no idea on how to pass a parameter...

Answer 1

you could just set a variable containing the filename:

fprintf(gp, "filename=\"%s\";load \"config\"\n", file_name);

and then reuse it in your Gnuplot script:

reset
set terminal png
set output "rp.png"
set title textcolor rgb "red" "R/P"
set yrange[0:110]
set xrange[0:110]
set xlabel "Rappel"
set ylabel "Précision"
set style data points
plot filename using 2:1 with linespoints