Plotting arrows with gnuplot

Question

I have data generated in a simulation. The generated data file looks something like this:

1990/01/01 99
1990/01/02 92.7
1990/01/03 100.3
1990/01/04 44.2
1990         


        

Answer 1

If you didn't want the arrow head then you might try the impulses style (with impulses rather than with lines) (If you still want the lines on top then you can plot twice).

If you really want the arrow heads then the following might help: It uses a for loop (or sorts) to add vertical arrows to a plot.

Gnuplot script, for loop within or adding to existing plot

Specifically:

create a file simloop.gp which looks like the following:

count  = count+1
#save the count to count.gp
system 'echo '.count.' > count.gp'
#load the simloop shell
system "./simloop.sh"

#draw the arrow
load 'draw_arrow.gp'

if(count

Then create a simloop.sh file that looks something like so

#!/bin/bash

#read the count
count=$(awk -F, '{print $1}' count.gp)
#read the file
xcoord=$(awk -v count=$count -F, 'BEGIN{FS=" ";}{ if(NR==count) print $1}' simulation.dat)
ycoord=$(awk -v count=$count -F, 'BEGIN{FS=" "}{ if(NR==count) print $2}' simulation.dat)
dir=$(awk -v count=$count -F, 'BEGIN{FS=" "}{ if(NR==count) print $3}' simulation.dat)

#choose the direction of the arrow
if [ \"$dir\" == \"0\" ]; then
    echo '' > draw_arrow.gp
fi

if [ \"$dir\" == \"1\" ]; then
  echo 'set arrow from ' $xcoord' ,0 to '$xcoord','$ycoord' head' > draw_arrow.gp
fi

if [ \"$dir\" == \"2\" ]; then
 echo 'set arrow from '$xcoord',0 to '$xcoord','$ycoord' backhead' > draw_arrow.gp
fi

Then create a simulation.gp file that looks something like so:

count = 0;
max = 5;
load "simloop.gp"
set yrange[0:*]
plot "simulation.dat" u 1:2 w l

Make sure the shell file has executable permissions (chmod +wrx simloop.sh), load up gnuplot and type

load "./simulation.gp"

This worked for me with the data file

1  99   0
2  92.7 1
3 100.3 2
4 44.2  0
5 71.23 1

(For testing I got rid of the time formatting You should be able to put it back without too much trouble.)

Then I got this graph:

Which I think is more or less what you want.