Trivial Graph Format is a simple text-based file format for describing graphs
Graph theory
In mathematics and computer science, graph theory is the study of graphs, mathematical structures used to model pairwise relations between objects from a certain collection. A "graph" in this context refers to a collection of vertices or 'nodes' and a collection of edges that connect pairs of...
In graph theory, a vertex or node is the fundamental unit out of which graphs are formed: an undirected graph consists of a set of vertices and a set of edges , while a directed graph consists of a set of vertices and a set of arcs...
definitions, which map node IDs to labels, followed by a list of edges, which specify node pairs and an optional edge label. Node IDs can be arbitrary identifiers, whereas labels for both nodes and edges are plain strings.
The graph may be interpreted as a directed or undirected graph. For directed graphs, to specify the concept of bidirectionality in an edge, one may either specify two edges (forward and back), or differentiate the edge by means of a label. For more powerful specification of graphs, see the other graph file formats below.
Example
A simple graph with 2 nodes and 1 edge might look like this:
1 First node
2 Second node
1 2 Edge between the two
Ease of use
TGF is useful for easily importing arbitrary data into a graph manipulation tool such as yEd
YEd
yEd is a freely available, general-purpose diagramming software with amulti-document interface.It is a cross-platform application written in Java that runs on Windows, Linux, Mac OS, or any platform that supports the JVM....
. Because of the simplicity of the format, it is straightforward to use small programs or scripts to convert domain-specific data to this general format. For example, given a Makefile like this:
It is possible to use a simple script, such as the following Python
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
program, to turn the Makefile dependencies into TGF output:
!/usr/bin/python
import fileinput, re
depends = {}
for line in fileinput.input:
m = re.match('(.+):\s*(.*)',line) # find every depenency line of the form ": "
if m:
item = m.group(1)
dependency_list = m.group(2)
print item,item # node definition
if dependency_list: # there are dependencies
depends[item] = dependency_list.split # store the list into a dictionary for later
print "#" # end of node list, start of edge list
for item in depends:
for dependency in depends[item]:
print item,dependency # edge definition
This will produce a TGF graph which can then be visualized and analyzed using a graph manipulation tool. The above content yields the following graph:
DOT is a plain text graph description language. It is a simple way of describing graphs that both humans and computer programs can use. DOT graphs are typically files that end with the .gv extension. The .gv extension is preferred, as .dot also is used by Microsoft Office 2003.Various programs...
, a plain text graph description language -- Graphviz
GraphML is an XML-based file format for graphs. The GraphML file format results from the joint effort of the graph drawing community to define a common format for exchanging graph structure data...
GXL is designed to be a standard exchange format for graphs. GXL is an extensible markup language sublanguage and the syntax is given by an XML document type definition...
, another graph exchange format based on XML -- GXL
Graph Modelling Language is a hierarchical ASCII-based file format for describing graphs. It has been also named Graph Meta Language.-Example:A simple graph in GML format:graph [ comment "This is a sample graph" directed 1 id 42...
is another widely used graph exchange format. -- GML
XGMML is an XML application based on GML which is used for graph description...
an XML-based graph markup language closely related to GML
GML
GML may refer to:* Middle Low German , a language used around the North Sea and the Baltic Sea from 1100 to 1600* Gostomel Airport , an international cargo airport, near Kiev, Ukraine* Gradient Multi-Layer nano-film...
