! Example of scatter plot with colorized dots.
! Author: Francois Tonneau

size 20 15

include palettes.gle

amove 4 3

set font ss hei 0.6

! Plot data.

begin graph
    size 13 10
    fullsize
    background "#f0f0f0"
    xaxis min 0.5 max 12.5 ftick 1 dticks 1
    yaxis min 28 max 72 ftick 30 dticks 10
    ticks length 0.15
    x2ticks off
    y2ticks off
    subticks off
    xnames Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    xtitle "Month" dist 0.7
    ytitle "Fahrenheit degrees" dist 0.8
    data "nottingham.dat"
    draw scatter                        ! plot monthly data with x jittering
    d21 line lwidth 0.04 color black    ! add line with 20-month averages
end graph

sub scatter
    local noise = 0.25
    local month, count, x, y, z, xp, yp
    for month = 1 to 20
        for count = 1 to ndata(d[month])
            x = dataxvalue(d[month], count)
            y = datayvalue(d[month], count)
            z = (y - 30) / (70 - 30)
            xp = xg(x) + rnd(noise) - noise/2
            yp = yg(y)
            amove xp yp
            set fill plasma(z)
            circle 0.10
        next count
    next month
end sub

! Add horizontal line with grand mean.

set lstyle 33
amove xg(1) yg(49.04)
aline xg(12) yg(49.04)