UNIX for Beginners Questions & Answers

2020-04;26.94
2020-05;26.92
2020-06;26.89
2020-07;27.01
2020-08;26.73
2020-09;26.72

reset

FILE = "LINEARFIT.txt"
set datafile separator ";"
set xdata time
set timefmt "%Y-%d"
set format x "%Y\n%d"

plot FILE u (StartDate=timecolumn(1)):0 index 0 every ::0:0:0

EndDate = strptime("%Y-%d","2020-20")
f(x) = a*(x-StartDate) + b
FIT_LIMIT = 1e-8
fit f(x) FILE u (timecolumn(1)):2 via a,b

set terminal png truecolor size 900,520 background rgb "#eff1f0"
set output "/xxx/xxx/xxx/xxx.png"
set xrange[StartDate:EndDate]
set grid xtics, ytics
set yrange[0:30]
set format y "%g"
myLabel(n) = sprintf("%g",n)

plot FILE u (timecolumn(1)):2 w lp pt 7 lc rgb "red" notitle, \
'' using 1:2:(myLabel($2)) w labels offset 0,-0.5 notitle, \
      f(x) ti "linear fit with extrapolation"