Can Gnuplot take different arguments at run time? maybe with Python?

Question

I have 500 files to plot and I want to do this automatically. I have the gnuplot script that does the plotting with the file name hard coded. I would like to have a loop that calls gnuplot every iteration with a different file name, but it does not seem that gnuplot support command line arguments.

Is there an easy way? I also installed the gnuplot-python package in case I can do it via a python script.However, I couldn't find the api so it's a bit difficult to figure out.

Thank you!

Answer 1

You can transform your gnuplot script to a shell script by prepending the lines

#!/bin/sh
gnuplot << EOF

appending the line

EOF

and substituting every $ by \$. Then, you can substitute every occurence of the filename by $1 and call the shell script with the filename as parameter.

Answer 2

Regarding the $'s in Sven Marnach's solution (the lines between EOF are called a "here script" in shell parlance): in my experience, one uses shell variables as usual, but $s that are meant for gnuplot itself must be escaped.

Here is an example:

for distrib in "uniform" "correlated" "clustered"
do
    gnuplot << EOF
    # gnuplot preamble omitted for brevity

    set output "../plots/$distrib-$eps-$points.pdf"
    set title "$distrib distribution, eps = $eps, #points = $points"

    plot "../plots/dat/$distrib-$eps-$points.dat" using 1:(\$2/$points) title "exact NN"
EOF

done

Note the backslash escaping the dollar so that gnuplot sees it.