C Interface for Making Visualized Graphs

1
C Interface for Making Visualized Graphs By
N.K. Bonsack and E.Harcourt
Abstract Software engineers and computer
scientists alike frequently come upon a problem
of how to store and easily retrieve large
quantities of data. The most common method is to
rely upon graphic structures such as binary
trees, linked lists, and even vectors. But when
it comes to displaying the data found within
these graphs, those engineers have to conceive of
a method to iterate through their graph and
display the contents within. My project seeks
to offer a far more user-friendly method of
displaying the contents of those graphs by means
of a class of functions which can iterate through
these graphs with as little input as possible on
the programmer's behalf and print out the
contents to an image file. To help with such a
complex task, I am using a software package
called GraphViz which can read in input defined
to its specifications and output a graph in jpeg,
gif or bmp format to be viewed in any recent
browser (Tsoukalos).
Methods I tested many hypotheses, among them
unconventional C methods such as templates,
inheritance, the friend design path and various
combinations of the above.
Conclusions
Many times this project was an exercise in
frustration because I had to actually work out
the hypotheses that I came up with to find that
they didnt work. After this exercise, I had to
go back to the very beginning and try out a new
hypothesis. Eventually after multitudinous
attempts and many hours, I was able to come up
with a simple solution that succeeded at keeping
the user from knowing anything about GraphViz
code.
Results After trying innumerable hypotheses, I
was able to write a class that could take in data
and lay it out as a graph as it would be
structured in the data structure itself.
Sample Input digraph g graph rankdir
"LR" node fontsize "16" shape
"ellipse" edge "node0" label "ltf0gt
0x10ba8 ltf1gt" shape "record" "node1"
label "ltf0gt 0xf7fc4380 ltf1gt ltf2gt
-1" shape "record" "node2" label "ltf0gt
0xf7fc44b8 2" shape "record" "node3"
label "ltf0gt 3.43322790286038071e-0644.7999877
92968750" shape "record" "node4" label
"ltf0gt 0xf7fc4380 ltf1gt ltf2gt 2" shape
"record" "node5" label "ltf0gt (nil)
-1" shape "record" "node6" label "ltf0gt
0xf7fc4380 ltf1gt ltf2gt 1" shape
"record" "node7" label "ltf0gt 0xf7fc4380
ltf1gt ltf2gt 2" shape "record" "node8"
label "ltf0gt (nil) -1" shape
"record" "node9" label "ltf0gt (nil)
-1" shape "record" "node10" label "ltf0gt
(nil) ltf1gt ltf2gt -1" shape
"record" "node11" label "ltf0gt (nil) ltf1gt
ltf2gt -1" shape "record"
"node12" label "ltf0gt 0xf7fc43e0 1" shape
"record" "node0"f0 -gt "node1"f0 id
0 "node0"f1 -gt "node2"f0 id
1 "node1"f0 -gt "node3"f0 id
2 "node1"f1 -gt "node4"f0 id
3 "node1"f2 -gt "node5"f0 id
4 "node4"f0 -gt "node3"f0 id
5 "node4"f1 -gt "node6"f0 id
6 "node4"f2 -gt "node10"f0 id
7 "node6"f0 -gt "node3"f0 id
8 "node6"f1 -gt "node7"f0 id
9 "node6"f2 -gt "node9"f0 id
10 "node7"f0 -gt "node3"f0 id
11 "node7"f1 -gt "node1"f0 id
12 "node7"f2 -gt "node8"f0 id
13 "node10"f1 -gt "node11"f0 id
14 "node10"f2 -gt "node12"f0 id
15 "node11"f2 -gt "node1"f0 id 16
Objectives I want to create an
interface which, ideally, requires as little
knowledge of GraphViz as possible. This interface
should be able to be something that can be used
by someone who is familiar with the usage of C
classes, in effect any person who has taken CS319
or has a moderate understanding of how to program
in C. This project should be as automated as
possible, ideally something that is completely
automatic.
Figure 3 Sample GraphViz graph showing the
hierarchy of UNIX operating systems using
randomized colors and shapes (Ellson).
References Ellson, John. (2005). Graphviz.
http//www.graphviz.org/Gallery.php Low, Glen.
(2005). Graphviz 1.13 (v16). Pixelglow GraphViz
http//www.pixelglow.com/graphviz/ Tsoukalos,
Mihalis, (2004). An Introduction to GraphViz.
Linux Journal. http//www.linuxjournal.com/article
/7275
Figure 2 GraphViz code that is fed into the
GraphViz interpreter to make the graph seen in
Figure 1.
Figure 1 Sample graph generated by GraphViz
which displays mappings between columns of data
(Low).