How to fix GNUPLOT replot issue - gnuplot

Question

I set-up a multiplot like this:
set terminal wxt size 1500,900
set format x "%d%m%y %H:%M:%S"
set xdata time
set timefmt x "%Y%m%dT%H%M%S"
set key font ",6"
set lmargin 10
set rmargin 10
set multiplot layout 2,1
plot "output.txt" u 1:2 w lines axes x1y1, \
"output.txt" u 1:3 w lines axes x1y2
plot "output.txt" u 1:40 w lines axes x1y1, \
"output.txt" u 1:39 w lines axes x1y2
set y2tics border
unset multiplot
Which works, and gives me 2 plots, one above the other.
But pressing the "replot" button (or using zoom) causes the second plot to fill the window - completely hiding the first plot.

Answer 1

Yes, that's how replot behaves. The documentation says: „Note that in multiplot mode, replot can only reproduce the most recent component plot, not the full set.“.
So, what you can do is to put the whole set multiplot ... unset multiplot stuff in an external file, load it, and then load it again. Or put that stuff in a string and eval it several times.

Answer 2

I had the same issue. Solved it with a loop:
set term wxt enh
do for [IDX = 0:1] {
if (IDX==1) {
set terminal png enhanced
set output 'temp.png'
}
set multiplot
set size 1,1
set origin 0,0
plot sin(x)
set size 0.5,0.35
set origin 0.13,0.63
plot cos(x)
unset multiplot
}
set output
set term wxt enh

Answer 3

Here is another workaround. It does not answer the question directly, but it could give idea to other similar issues. Put header, and a footer 'reread', then two context could be choosen for a similar multiplot (done twice)
if (exists("rehearse")) rehearse=1+rehearse; set term x11
if (!exists("rehearse")) rehearse=0; set term png; set output sprintf("test_palette_%s.png", system("date +\"%F\""))
pr "rehearse=".rehearse; show term #<= comment printing
set samples 100; set isosample 100,100
set xrange [0:1]; set yrange [0:1]
set palette defined (0 "white", 1 "red")
set autoscale cbfix; unset colorbox; unset key
set multiplot layout 2,2
plot '++' using 1:2:1 with image
plot '++' using 1:2:2 with image
plot '++' using 1:2:(-$1) with image
plot '++' using 1:2:(-$2) with image
unset multiplot
if(rehearse < 1) reread