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GEXF

GEXF (Graph Exchange XML Format) is an XML-based format for exchanging graph structures, attributes and visualization metadata. It supports static and dynamic graphs, typed attributes (including list types), hierarchical structures and a visualization (viz) module for styling nodes and edges. The official reference and examples are available at https://gexf.net.

Minimal (Hello world) example​

A minimal static directed graph with 2 nodes and 1 edge:

<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://gexf.net/1.3" version="1.3">
  <graph mode="static" defaultedgetype="directed">
    <nodes>
      <node id="0" label="Hello" />
      <node id="1" label="World" />
    </nodes>
    <edges>
      <edge source="0" target="1" />
    </edges>
  </graph>
</gexf>

Header and metadata​

Typical recommended header that includes XML Schema references and meta data:

<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://gexf.net/1.3"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://gexf.net/1.3
                           http://gexf.net/1.3/gexf.xsd"
       version="1.3">
  <meta lastmodifieddate="2009-03-20">
    <creator>Gephi.org</creator>
    <description>A sample GEXF file</description>
  </meta>
  ...
</gexf>

The meta element is useful to store creator, description, keywords and last-modified date. Including the schema location is recommended for validation.

Attributes and associated data​

GEXF allows declaring typed attributes for nodes and edges inside attributes elements. Supported primitive types follow XSD (string, integer, float, double, boolean, date, anyURI) and additional types (liststring, listinteger, bigdecimal, etc.) are defined by the spec.

Attributes declaration example and node attribute usage:

<graph defaultedgetype="directed">
  <attributes class="node">
    <attribute id="0" title="url" type="string"/>
    <attribute id="1" title="indegree" type="float"/>
    <attribute id="2" title="frog" type="boolean">
      <default>true</default>
    </attribute>
  </attributes>

  <nodes>
    <node id="0" label="Gephi">
      <attvalues>
        <attvalue for="0" value="http://gephi.org"/>
        <attvalue for="1" value="1"/>
      </attvalues>
    </node>
    <node id="1" label="Webatlas">
      <attvalues>
        <attvalue for="0" value="http://webatlas.fr"/>
        <attvalue for="1" value="2"/>
      </attvalues>
    </node>
  </nodes>
</graph>

List attributes​

GEXF supports list types such as liststring and listint. List values are written as comma-separated values inside brackets, e.g. [foo, bar].

Topology: nodes, edges, parallel edges​

  • Nodes: declared with <node id="..." label="..."/> where id must be unique.
  • Edges: declared with <edge source="..." target="..."/> and optional attributes such as id, weight (double), type (directed/undirected/mutual).
  • Parallel edges (multigraphs): supported via an additional kind attribute that distinguishes parallel edges; source-target-kind must be unique.

Example of parallel edges:

<edge source="0" target="1" weight="1.0" kind="friend"/>
<edge source="0" target="1" weight="1.0" kind="neighbor"/>

Dynamics (graphs over time)​

GEXF supports dynamic graphs via the mode="dynamic" attribute on <graph>. Time can be represented with intervals (default) or timestamps (use timerepresentation="timestamp"). The timeformat attribute controls encoding (e.g. double, date, dateTime).

A dynamic graph example:

<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://gexf.net/1.3"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://gexf.net/1.3
                             http://gexf.net/1.3/gexf.xsd"
       version="1.3">
  <graph mode="dynamic" defaultedgetype="directed" timeformat="date">
    <attributes class="node" mode="static">
      <attribute id="0" title="url" type="string"/>
      <attribute id="1" title="frog" type="boolean"><default>true</default></attribute>
    </attributes>
    <attributes class="node" mode="dynamic">
      <attribute id="2" title="indegree" type="float"/>
    </attributes>

    <nodes>
      <node id="0" label="Gephi" start="2009-03-01">
        <attvalues>
          <attvalue for="0" value="http://gephi.org"/>
          <attvalue for="2" value="1"/>
        </attvalues>
      </node>
      <node id="1" label="Webatlas">
        <attvalues>
          <attvalue for="0" value="http://webatlas.fr"/>
          <attvalue for="2" value="1" end="2009-03-01"/>
          <attvalue for="2" value="2" start="2009-03-01" end="2009-03-10"/>
          <attvalue for="2" value="1" start="2009-03-11"/>
        </attvalues>
      </node>
    </nodes>

    <edges>
      <edge source="0" target="1" start="2009-03-01"/>
      <edge source="0" target="2" start="2009-03-01" end="2009-03-10"/>
    </edges>
  </graph>
</gexf>

Spells and timestamps​

  • Use <spells> with <spell start="..." end="..."/> to express multiple disjoint intervals for a node/edge.
  • Alternatively use compact timestamps or intervals attributes (parser-dependent).
  • Intervals are inclusive. start/end may be omitted to represent an unbounded side (infinite bound).

Visualization module (VIZ)​

The VIZ module extends GEXF with a viz namespace (xmlns:viz="http://gexf.net/1.3/viz") and allows attaching color, position, size and shape metadata to nodes and edges. Gephi supports the VIZ module for styling.

Node viz example:​

<gexf xmlns="http://gexf.net/1.3" xmlns:viz="http://gexf.net/1.3/viz">
  <graph>
    <nodes>
      <node id="a" label="glossy">
        <viz:color r="239" g="173" b="66" a="0.6"/>
        <viz:position x="15.783598" y="40.109245" z="0.0"/>
        <viz:size value="2.0375757"/>
        <viz:shape value="disc"/>
      </node>
    </nodes>
  </graph>
</gexf>

Edge viz example:​

<edge id="e1" source="n0" target="n1">
  <viz:color r="157" g="213" b="78"/>
  <viz:thickness value="5.124"/>
  <viz:shape value="solid"/>
</edge>
  • Colors: RGBA (r,g,b integers 0–255; a float 0.0–1.0) or hex="#RRGGBB".
  • Position: x, y, z floats (Gephi treats z as optional height).
  • Size/Thickness: non-negative floats.
  • Shapes: nodes (disc, square, triangle, diamond, image), edges (solid, dotted, dashed, double).

Note: Viz attributes are not dynamic in GEXF 1.3; to represent viz over time use slices or multiple graphs.

Best practices & parser advice​

  • Always place <edges> after <nodes> to avoid parser errors.
  • Use count attributes in <nodes> and <edges> to help parsers allocate memory.
  • Prefer liststring for repeated textual attributes when applicable.
  • Set idtype on <graph> to hint if IDs are integers or strings for optimization.
  • Validate files using the GEXF XSD when possible.

MIME type​

When serving GEXF over HTTP use Content-Type: application/gexf+xml.

Resources & references​