DOT is a graphdescription language. DOT graphs are typically files with the filename extensiongv or dot. The extension gv is preferred, to avoid confusion with the extension dot used by versions of Microsoft Word before 2007. Various programs can process DOT files. Some, such as dot, neato, twopi, circo, fdp, and sfdp, can read a DOT file and render it in graphical form. Others, such as gvpr, gc, acyclic, ccomps, sccmap, and tred, read DOT files and perform calculations on the represented graph. Finally, others, such as lefty, dotty, and grappa, provide an interactive interface. The GVedit tool combines a text editor with noninteractive image viewer. Most programs are part of the Graphviz package or use it internally.
Syntax
Graph types
Undirected graphs
At its simplest, DOT can be used to describe an undirected graph. An undirected graph shows simple relations between objects, such as friendship between people. The graph keyword is used to begin a new graph, and nodes are described within curly braces. A double-hyphen is used to show relations between the nodes. // The graph name and the semicolons are optional graph graphname
Directed graphs
Similar to undirected graphs, DOT can describe directed graphs, such as flowcharts and dependency trees. The syntax is the same as for undirected graphs, except the digraph keyword is used to begin the graph, and an arrow is used to show relationships between nodes. digraph graphname
Attributes
Various attributes can be applied to graphs, nodes and edges in DOT files. These attributes can control aspects such as color, shape, and line styles. For nodes and edges, one or more attribute–value pairs are placed in square brackets after a statement and before the semicolon. Graph attributes are specified as direct attribute–value pairs under the graph element, where multiple attributes are separated by a comma or using multiple sets of square brackets, while node attributes are placed after a statement containing only the name of the node, but not the relations between the dots. graph graphname
HTML-like labels are only available on versions of Graphviz that are newer than mid-November 2003, in particular, they are not considered as part of release 1.10.
Comments
Dot supports C and C++ style single line and multiple line comments. In addition, it ignores lines with a number sign symbol as their first character. // This is a single line comment. /* This is a multiple line comment. */ # Lines like this are also ignored.
A simple example
Following is an example script that describes the bonding structure of an ethane molecule. This is an undirected graph and contains node attributes as explained above. graph ethane
Layout programs
The DOT language defines a graph, but does not provide facilities for rendering the graph. There are several programs that can be used to render, view, and manipulate graphs in the DOT language:
General
Graphviz – a collection of libraries and utilities to manipulate and render graphs
d3-graphviza JavaScript library based on Viz.js and D3.js that renders DOT graphs and supports animated transitions between graphs and interactive graph manipulation
Vis.jsa JavaScript library that accept DOT as input for network graphs.
Viz.js – a JavaScript port of Graphviz that provides a simple wrapper for using it in the browser.
It is possible to specify layout details with DOT, although not all tools that implement the DOT language pay attention to the position attributes. Thus, depending on the tools used, users must rely on automated layout algorithms or tediously hand-positioned nodes. For example: digraph g
There are two problems in the image titled "An image that seems improperly rendered". The square on the right is not a perfect square and some labels are not next to the related arrow and some overlap the arrows. This can be fixed with Inkscape or other SVG editors. In some cases, this can also be fixed by using the pos attribute to specify a position, and the weight attribute to square the graph.
