# Define an adjustable-width mark that indicates grouping
# Hiroki Motoyoshi 2024
set title "Adjustable width mark used to indicate grouping"
set title offset 0,2
$bar_data_in <<EOD
# Name Value
A 2
B 5
C 7
D 6
E 4
F 2
G 7
H 3
I 6
J 7
K 8
L 5
M 3
EOD
stats $bar_data_in using 2 nooutput
n = STATS_blank + 1
array member[n]
do for [i=1:n] {
member[i] = 0
}
set table $bar_data
plot $bar_data_in using (strcol(1)):2:(idx = column(-1)+1, member[idx]=member[idx]+1,idx) with table
unset table
set print $group_data
offset = 1
do for [i=1:4] {
print sprintf('"Group %i" %i %i', i, member[i], offset)
offset = offset + member[i] + 1
}
unset print
set tmargin sc 0.8
set bmargin sc 0.2
set autoscale xfix
set yrange [0:*]
set offsets gr 0.05, gr 0.05, gr 0.1
unset key
set xtics nomirror
set ytics 0,1,8 nomirror
# "set border 3" would extend the y axis verticallay to include the marks.
# Setting explicit yrange [0:8] would put the marks out of range.
# So we replace the left-hand border with an arrow from y=0 to y=8
set border 1
set arrow from graph 0, first 0 to graph 0, first 8 nohead
# Description of a single mark consisting of a half-height horizontal square bracket
# with a centered vertical bar above it:
#
# |
# |⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺⎺|
#
# When plotted, the using specfier will provide x, y, width, height
$group_mark <<EOD
# x y 1=stroke
0 -0.5 1
0 0 1
1 0 1
1 -0.5 1
0.5 0.0 1
0.5 0.5 1
EOD
set mark 1 $group_mark
plot $bar_data using ($0+$3):2:(0.8):3:xtic(1) \
with boxes lc variable fill solid 0.3, \
$group_data using ($3-0.5):(9):2:(1) \
with marks mt 1 units xy lt -1 lw 1, \
$group_data using ($3-0.5+$2/2):(9):1 \
with labels center offset 0,1.7
Click here for minimal script to generate this plot
