I have generated this picture with Gnuplot, shortly by means the flags below for the palette and plot:
set palette defined ( 0 "green", 1 "blue", 2 "blue", 3 "orange" )
plot "10steps_500" u 1:2:3 w p pt 7 ps 2.0 lt pal, "10steps_500-300" u 1:2:3 w p pt 7 ps 2.0 lt pal
However, I wanna bring the blue point to front. Someone knows how can we do it in gnuplot?