#
# Use an array to hold the sum of values in each column
#
array Sum[20]
do for [i=5:13] { 
  stats 'immigration.dat' skip 2 using (column(i)) nooutput
  Sum[i] = STATS_sum
  print sprintf("Sum[%2d] = %d",i,Sum[i])
}
#
# Use the stored sum to normalize values in each colum
#
set style fill transparent solid 0.2 border -1
set style data filledcurve y=0
set tics scale 0
set xrange [] noextend
set xlabel "Decade"
set title "Use of an array to aid normalization and to plot summed values"

set multiplot
plot for [i=5:13] 'immigration.dat' using 1:(column(i)/Sum[i]) title columnhead

#
# Plot the array values themselves in a separate inset
#

set size 0.4, 0.3
set origin 0.05, 0.6

unset xtics
unset ytics
set border 0
set xlabel "Total"
set xrange [4:15]
set yrange [0:*]
unset title
set boxwidth 1.0 absolute

plot Sum using 1:2:($1-4) with boxes lc variable notitle

unset multiplot


Click here for minimal script to generate this plot

set title "Fit function to values stored in an array"
set xtics nomirror

array A[100]
do for [i=1:100] { A[i] = sin(2*pi*i/100.) + 0.1*rand(0) }
a = b = c = 0.01
set key title "before fit"
plot A with points title "Array A", c+cos(a+b*x) with lines


Click here for minimal script to generate this plot

set fit nolog
fit c+cos(a+b*x) A using 1:2 via a,b,c

set key title "after fit"
plot A with points title "Array A", c+cos(a+b*x) with lines


Click here for minimal script to generate this plot

#
# Illustrate loading an array from a data file
# This could be done using a preliminary 'plot' command, perhaps together
# with 'set table' if you don't actually want generate a plot, but here
# we use 'stats'. The first run is just to pick up the array size needed.
# The second run stores one value into each array element.
#
set title "Illustrate loading an array from a column in a data file\n".\
          "Note that first data point in the file is 'line 0'\n".\
          "but it goes into array element Data[1]"

set yrange [0:20]
set border 3
set tics nomirror
set key left center nobox

FILE = 'orbital_elements.dat'

stats FILE index 2 using 2 prefix "A"
array Data[A_records]

stats FILE index 2 using (Data[int($0+1)] = $2) prefix "B"

plot FILE index 2 using 2 title "Data from file" with lines lw 2, \
     Data using 0:2:(sprintf("Data[%d]",$1)) with labels point pt 6 ps 2 center offset 0,1 title "Data[i]"


Click here for minimal script to generate this plot