# set terminal pngcairo  background "#ffffff" enhanced font "arial,10" fontscale 1.0 size 600, 400 
# set output 'pointsize.2.png'
unset border
unset key
set view map
set style data lines
set noxtics
set noytics
set noztics
set title "splot with variable size points\nit is possible to specify size and color separately" 
splot 'world.dat' using 1:2:(0) with lines lt 3,       'world.cor' using 1:2:(0.5-rand(0)):(5.*rand(0)) with points pt 5 ps var lt palette