How to plot tree/graph/web data on gnuplot? - graph

Question

I have a data-set that consist of edges and colors, and I want to plot them on a web-like manner, with lines and circles such as the picture below, and possibly with cluster coloring.
The data is organized like this:
point1a_x point1a_y color
point1b_x point1b_y color
point2a_x point2a_y color
point2b_x point2b_y color
(...)
point2n_x point2n_y color
point2n_x point2n_y color
How would I go about doing it on gnuplot?

Answer 1

Okay, so I figured it out myself and I'll leave the details here to help anyone with the same questions.
Single color graph with labels on the nodes:
This will generate a graph much like the one on the question, with lines connecting circles with labels inside.
plot 'edges.dat' u 1:2 with lines lc rgb "black" lw 2 notitle,\
'edges.dat' u 1:2:(0.6) with circles fill solid lc rgb "black" notitle,\
'edges.dat' using 1:2:($0) with labels tc rgb "white" offset (0,0) font 'Arial Bold' notitle
With little changes it can exaclty match the one on the question picture.
plot 'edges.dat' u 1:2 with lines lc rgb "black" lw 2 notitle,\
'edges.dat' u 1:2:(0.8) with circles linecolor rgb "white" lw 2 fill solid border lc lt 0 notitle, \
'edges.dat' using 1:2:($0) with labels offset (0,0) font 'Arial Bold' notitle
Cluster-colored graph:
unset colorbox
set palette model RGB defined ( 0 0 0 0 , 1 1 0 0 , 2 1 0.9 0, 3 0 1 0, 4 0 1 1 , 5 0 0 1 , 6 1 0 1 )
plot 'edges.dat' u 1:2:3 with lines lc palette notitle,\
'edges.dat' u 1:2:(0.15):3 with circles fill solid palette notitle
The data used on all plots follow this structure:
21.53 9.55 0
24.26 7.92 0
5.63 3.23 1
2.65 1.77 1
5.63 3.23 0
4.27 7.04 0
(...)

Answer 2

The accepted answer didn't quite work out for me. Here is how I had to change it:
The format of the input file
# A vertex has 3 fields: x coordinate, y coordnate and the label
# An edge consists of two points in consecutive lines
# There must be one or more blank lines between each edge.
21.53 9.55 A
24.26 7.92 B
5.63 3.23 C
2.65 1.77 D
5.63 3.23 C
4.27 7.04 E
#...
The big difference compared to the other answer is that the labels belong to vertices, not edges.
Also note that I changed the labels to letters instead of numbers. Labels can be any string and this makes it clearer that they are not sequential indexes in the example.
The plotting command
plot \
'edges.dat' using 1:2 with lines lc rgb "black" lw 2 notitle,\
'edges.dat' using 1:2:(0.6) with circles fill solid lc rgb "black" notitle,\
'edges.dat' using 1:2:3 with labels tc rgb "white" offset (0,0) font 'Arial Bold' notitle
Big change here is that now when plotting the labels we plot the 3rd field instead of the $0 field, which is a sequential number.

Answer 3

I came across this question and thought the data input can be made more user-friendly. In case you need to change x,y coordinates of a certain point you probably don't want to search through all connectors and change the coordinates everywhere accordingly. So, instead the example below is working with node IDs and connecting lines between two IDs.
The x,y coordinates and colors are stored in a string and the function strstrt() is used to create a lookup. The script below is a starting point and can be expanded, e.g. dashed lines, different point shapes, string labels, etc.
The datafile looks like this:
first block: IDs with x,y coordinates and color
second block, separated by two(!) blank lines: IDs to be connected and color of the line.
Data: SO20406346.dat
# ID x y PointColor
1 2.0 8.0 0xffaaaa
2 6.0 9.0 0xaaffaa
3 9.0 6.0 0xaaaaff
4 5.0 5.0 0xffaaff
5 6.0 2.0 0xffffaa
6 1.0 1.0 0xaaffff
73 9.2 1.3 0xcccccc
A 8.0 8.0 0xcccccc
XY 2.0 4.0 0xcccccc
# ID1 ID2 LineColor
1 4 0x0000ff
2 4 0x000000
3 4 0x00ff00
4 4 0x000000
5 4 0x000000
6 5 0xff0000
73 3 0xcccccc
73 4 0xcccccc
73 5 0xcccccc
A 2 0xcccccc
A 3 0xcccccc
XY 1 0xcccccc
XY 4 0xcccccc
XY 6 0xcccccc
Edit: changed to work with string "IDs" as well.
Script: (works for gnuplot>=4.6.0, March 2012)
### plot a node graph
reset
FILE = "SO20406346.dat"
IdIdxs = XYs = ' '
stats FILE u (IdIdxs=IdIdxs.sprintf("%s:%d ",strcol(1),$0), \
XYs=XYs.sprintf("%g %g ",$2,$3)) index 0 nooutput
Px(i) = real(word(XYs,2*i+1))
Py(i) = real(word(XYs,2*i+2))
getIdx(col) = (c0=strstrt(IdIdxs,sprintf(" %s:",strcol(col))), \
c1=strstrt(IdIdxs[c0+1:],' ')+c0, \
s0=IdIdxs[c0:c1], c2=strstrt(s0,':'), int(s0[c2+1:]))
set size ratio 1
set key noautotitle
set offsets 0.25,0.25,0.25,0.25
plot FILE index 1 u (idx0=getIdx(1),x0=Px(idx0)):(y0=Py(idx0)): \
(idx1=getIdx(2),Px(idx1)-x0):(Py(idx1)-y0):3 w vec lw 2 lc rgb var nohead, \
'' index 0 u 2:3:4 w p pt 7 ps 6 lc rgb var, \
'' index 0 u 2:3 w p pt 6 ps 6 lc rgb "black", \
'' index 0 u 2:3:1 w labels
### end of script
Result: