Trivial Graph Format

Trivial Graph Format (TGF) is a simple text-based adjacency list file format for describing graphs,[1] widely used because of its simplicity.[2]


The format consists of a list of node definitions, which map node IDs to labels, followed by a list of edges, which specify node pairs and an optional edge label. Because of its lack of standardization, the format has many variations.[1] For instance, some implementations of the format require the node IDs to be integers,[3] while others allow more general alphanumeric identifiers.

Each node definition is a single line of text starting with the node ID, separated by a space from its label. The node definitions are separated from the edge definitions by a line containing the "#" character. Each edge definition is another line of text, starting with the two IDs for the endpoints of the edge separated by a space. If the edge has a label, it appears on the same line after the endpoint IDs.[3]

The graph may be interpreted as a directed or undirected graph. For directed graphs, to specify the concept of bi-directionality in an edge, one may either specify two edges (forward and back) or differentiate the edge by means of a label.


A simple graph with two nodes and one edge might look like:

1 First node
2 Second node
1 2 Edge between the two

See also

  • yEd, a graph editor that can handle TGF file format.


  1. Roughan, Matthew; Tuke, Jonathan (August 2015), "The Hitchhikers Guide to Sharing Graph Data" (PDF), 2015 3rd International Conference on Future Internet of Things and Cloud, IEEE, doi:10.1109/ficloud.2015.76
  2. Pitas, Ioannis (2016), "1.5 Graph storage formats and visualization", Graph-Based Social Media Analysis, Chapman & Hall/CRC Data Mining and Knowledge Discovery Series, 39, CRC Press, p. 14, ISBN 9781498719056
  3. Canabrava, Tomaz; Cord-Landwehr, Andreas (April 10, 2016), "Chapter 4. Import and Export", The Rocs Handbook, Revision Rocs 2.1.50 (Applications 16.04)

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