Calling gnuplot from Lua

gnuplot.lua

local function plot(series, tpause)
   local gp = io.popen("gnuplot", 'w')

   local lines = { }
   for k,v in pairs(series) do
      table.insert(lines, string.format(" '-' u 1:2 title '%s'", k))
   end
   
   gp:write("plot" .. table.concat(lines, ",") .. "\n")
   for k,v in pairs(series) do
      for i=1,#v do
	 gp:write(string.format("%f %f\n", i, v[i]))
      end
      gp:write("e\n")
   end

   gp:write(string.format("pause %f\n", tpause or 100.0))
   gp:close()
end