[gnuplot] for loop & obj (circle, rec)

1. object (circle or rec)

set object circle 

set object rec

http://gnuplot.sourceforge.net/demo/circles.html

2. file name for loop

https://stackoverflow.com/questions/25257202/how-to-define-a-gnuplot-output-file-as-a-variable

set palette defined ( -1 "blue", 0 "#999999", 1 "red" ) 

p for [i=10:90] g = 0.01*i  sprintf('test_%g', g) u 1:3:g w l lc palette   t ''

3. define palette

http://gnuplot.sourceforge.net/demo/pm3dcolors.html

set palette defined ( 0 "green", 1 "blue", 2 "red", 3 "orange" ) 

4. line color from variable

http://www.gnuplotting.org/using-a-palette-as-line-color/

plot 'test.txt' u 1:2:2 w l lc palette