Unique key and same size of graphs using multiplots [duplicate] - gnuplot

Question

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Place key below multiplot graph in gnuplot
(2 answers)
Closed 8 years ago.
I want to put this two graphs together and I would like to use only one key. If I set one with notitle I could get them with only key, however the shape of the graphs will change.
set term postscript eps
set output "temp.eps"
set multiplot layout 1,2
set xtics ("32" 0, "128" 2, "512" 4, "2048" 6, "8192" 8)
#set grid ytics
set xrange [0:8]
set yrange [0:100]
p "8" u ($0):($6) w lp ps 0.75 notitle, "10" u ($0):($6) w lp lc rgb "#228B22" ps 0.75 notitle, "12" u ($0):($6)w lp lc rgb "black" ps 0.75 notitle , "14" u ($0):($6)w lp lc rgb "blue" ps 0.75 notitle, "16" u ($0):($6) w lp lc rgb "#D2691E" ps 0.75 notitle, "18" u ($0):($6)w lp lc rgb "#8A2BE2" ps 0.75 notitle, "20" u ($0):($6) w lp lc rgb "#20B2AA" ps 0.75 notitle
set xtics ("32" 0, "128" 2, "512" 4, "2048" 6, "8192" 8)
#set grid ytics
set xrange [0:8]
set yrange [0:100]
set xlabel "nel"
#set key location
set key invert
set key reverse
set key center right
set key outside
p "8" u ($0):($6) w lp ps 0.75 title "8", "10" u ($0):($6) w lp lc rgb "#228B22" ps 0.75 title "10", "12" u ($0):($6)w lp lc rgb "black" ps 0.75 title "12", "14" u ($0):($6)w lp lc rgb "blue" ps 0.75 title "14", "16" u ($0):($6) w lp lc rgb "#D2691E" ps 0.75 title "16", "18" u ($0):($6)w lp lc rgb "#8A2BE2" ps 0.75 title "18", "20" u ($0):($6) w lp lc rgb "#20B2AA" ps 0.75 title "20"
unset multiplot
This would produce something like:
As it can be seen, the shape of one graph would change due to the legend on its right. I looking for a way of using only legend and both figures using the shape of the graph on the left.

Answer 1

This question has two parts which I will address separately.
1) Can I use the same key for multiple plots?
No, unless the key would happen to be the same for the data in both plots anyway. For example, two plots with two lines each where the two lines would have the titles 'one' and 'two' in both plots could share the same key; two plots with one line each with the titles 'one' and 'two' in the separate plots could not share the same key.
2) How do I get my multiplots to be the same size when I have a key?
There is no easy way to do this, either you manually adjust the sizes of the plots, or you set up functions like in this answer.
In your case, it could look something like:
#!/usr/bin/env gnuplot
### n: change this parameter to equal the number of data sets to be plotted
n = 2
# l: left margin in pixels
l = 75.0
# k: key height in pixels (right margin)
k = 150.0
# m: margin between plots
m = 40.0
# p: plot width
p = 300.0
# w: width of output in pixels
w = p*n + m*(n-1) + l + k
### functions to help set top/bottom margins
lft(i,n,w,l,k) = (l+(w-l-k)*(i-1)/n)/w
rgt(i,n,w,l,k) = (l+(w-l-k)*i/n - m)/w
### first set up some basic plot parameters
set term pngcairo enhanced size w,600
set output 'multikey.png'
set ylabel 'Y Axis'
set xlabel 'X Axis'
set multiplot layout 1,(n+1) title 'Main title'
### First plot
# change only plot command here
currentplot = 1
set lmargin at screen lft(currentplot,n,w,l,k)
set rmargin at screen rgt(currentplot,n,w,l,k)
unset key
plot sin(1*x) notitle, \
sin(2*x) notitle
unset ylabel
### Middle data plot (commented out for this example)
# copy and paste this code to make more middle plots
#currentplot = currentplot + 1
#set lmargin at screen lft(currentplot,n,w,l,k)
#set rmargin at screen rgt(currentplot,n,w,l,k)
#unset title
#replot
### Last data plot
# change only plot command here
currentplot = currentplot + 1
set lmargin at screen lft(currentplot,n,w,l,k)
set rmargin at screen rgt(currentplot,n,w,l,k)
set xtics
replot
### Key plot
set lmargin at screen rgt(n,n,w,l,k)
set rmargin at screen 1
set key center center
set border 0
unset tics
unset xlabel
unset ylabel
set yrange [0:1]
plot 2 t 'Line 1', \
2 t 'Line 2'
unset multiplot
The result looks like this:

Answer 2

Note that I just provided example code. You might need to change it to get a proper plot.
You can set the size of the individual plots in multiplot using the following example: (It is an example , you might have to work with to get a correct size for your plots.)
set size 0.8,1.2
Try setting it for each of the individual plots.
You can set the overall size by
set terminal postscript enhanced eps 24 color size 10cm,15cm