Gnuplot Thick Curve Exceeds Plot Boundary

Question

I've plotted the following in Gnuplot. My issue is that the curves exceed the boundary (so we can see that the purple and blue curves go beyond the y-axis). Any way to solve this problem? I'm hoping there is something that restricts drawing to inside the plotting area. Sure I can just plot less of the curve but that then looks weird. Ideally, I want Gnuplot to go around the frame of the curve and remove any bits of the curve that are there.

I've made the purple curve abnormally fat just to illustrate the problem. The problem is also there with the blue curve though.

The code to produce the above plot is:

#!/usr/bin/env gnuplot

### n: change this parameter to equal the number of data sets to be plotted
n = 2
# t: top margin in pixels
t = 25.0
# b: key height in pixels (bottom margin)
b = 25.0
# h: height of output in pixels
h = 150.0*n + t + b

### define functions to help set top/bottom margins
top(i,n,h,t,b) = 1.0 - (t+(h-t-b)*(i-1)/n)/h
bot(i,n,h,t,b) = 1.0 - (t+(h-t-b)*i/n)/h

### first set up some basic plot parameters
#set term cairolatex size 15cm,15cm
#set output 'DifferentialAmplifierPlot.tex'

set term pdfcairo size 15cm,15cm
set output 'DifferentialAmplifierPlot.pdf'

set border lw 4

set grid mxtics mytics xtics ytics ls '-1' ls '-1' lc rgb 'gray70', lc rgb 'gray90'

set mxtics
set mytics

# Make yrange > ytics > function to get padding.
set yrange [-1.5:1.5]
set ytics ("" -1.5, -1.25 1, -1.0, -0.75 1, -0.5, -0.25 1, 0.0, 0.25 1, 0.5, 0.75 1, 1.0, 1.25 1, "" -1.5)

set xtics 0,1,5
set xrange [0:5]

set xtics
set mxtics
set mytics

set format x ""
set grid xtics ytics mxtics mytics ls -1 ls -1 lc rgb 'gray60', lc rgb '#C0E5E5E5''

set multiplot layout (n+1),1 #font ",14" title 'Input And Output Voltages Of Differential Amplifier'

### First plot
# change only plot command here
currentplot = 1
set tmargin at screen top(currentplot,n,h,t,b)
set bmargin at screen bot(currentplot,n,h,t,b)
unset key
unset xlabel
set title 'Input (Bottom) And Output (Top) Voltages Of The Differential Amplifier'
set ylabel 'Voltage [V]'
plot 'DifferentialAmplfier.dat' using (1000*$1):2 with lines lw 20 lc rgb 'dark-magenta'

### Last plot
# change only plot command here
currentplot = currentplot + 1
set tmargin at screen top(currentplot,n,h,t,b)
set bmargin at screen bot(currentplot,n,h,t,b)
set format x
unset title
set xlabel 'Time [ms]'
set ylabel 'Voltage [mV]'
plot 'DifferentialAmplfier.dat' using (1000*$1):(1000*$3) with lines lw 10 lc rgb 'navy'

unset multiplot

set term x11

Questionable/Dodgy fix...

Answer 1

There is a way to do this but it is cumbersome. You would use a multiplot, plot your data, then through judicious use of the graph and screen coordinate systems plot white rectangles around your plot, then replot an empty plot to redraw the borders (because the rectangles will have overwritten your labels and half of the border line thickness). Here is an MWE:

#!/usr/bin/gnuplot -persist

reset
f(x) = sin(x)

xl=0; xh=20; yl=-1; yh=1;
set xrange [xl:xh]
set yrange [yl:yh]

set multiplot

plot f(x) not w l lt 3 lw 12

## overdraw borders on left, right, top, bottom
set object 1 rectangle from screen 0, screen 0 to graph 0, screen 1 behind \
  fillstyle solid noborder
set object 2 rectangle from graph 1, screen 0 to screen 1, screen 1 behind \
  fillstyle solid noborder
set object 3 rectangle from screen 0, graph 1 to screen 1, screen 1 behind \
  fillstyle solid noborder
set object 4 rectangle from screen 0, screen 0 to screen 1, graph 0 behind \
  fillstyle solid noborder

plot NaN not

unset multiplot