Understanding the GEXF Format

GEXF (Graph Exchange XML Format) is an XML-based file format for representing graph structures. It was created for the Gephi graph visualization platform but is now widely used across many graph tools.

Basic Structure

A GEXF file has this structure:

<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://www.gexf.net/1.2draft" version="1.2">
    <meta lastmodifieddate="2024-01-15">
        <creator>Your Tool Name</creator>
        <description>Description of the graph</description>
    </meta>
    <graph mode="static" defaultedgetype="directed">
        <attributes class="node">
            <!-- Node attribute definitions -->
        </attributes>
        <attributes class="edge">
            <!-- Edge attribute definitions -->
        </attributes>
        <nodes>
            <!-- Node elements -->
        </nodes>
        <edges>
            <!-- Edge elements -->
        </edges>
    </graph>
</gexf>

Elements

The `<gexf>` Root Element

The root element declares the namespace and version:

<gexf xmlns="http://www.gexf.net/1.2draft" version="1.2">

Supported versions:

1.1 - Older format
1.2 - Most common, widely supported
1.3 - Latest version

The `<meta>` Element

Optional metadata about the file:

<meta lastmodifieddate="2024-01-15">
    <creator>Gephi 0.10.1</creator>
    <description>Social network analysis</description>
</meta>

Element	Description
`lastmodifieddate`	Date in YYYY-MM-DD format
`creator`	Tool or person who created the file
`description`	Human-readable description

The `<graph>` Element

Defines the graph structure:

<graph mode="static" defaultedgetype="directed">

Attribute	Values	Description
`mode`	`static`, `dynamic`	Whether the graph changes over time
`defaultedgetype`	`directed`, `undirected`, `mutual`	Default edge direction

Attribute Definitions

Before using attributes on nodes or edges, you must declare them:

<attributes class="node">
    <attribute id="0" title="type" type="string"/>
    <attribute id="1" title="weight" type="float"/>
    <attribute id="2" title="active" type="boolean">
        <default>true</default>
    </attribute>
</attributes>

Supported types:

string - Text values
integer - Whole numbers
float / double - Decimal numbers
boolean - true/false
date - Date values

Node Elements

<nodes>
    <node id="n1" label="Web Server">
        <attvalues>
            <attvalue for="0" value="server"/>
            <attvalue for="1" value="1.5"/>
        </attvalues>
    </node>
</nodes>

Attribute	Required	Description
`id`	Yes	Unique identifier
`label`	No	Human-readable name

Edge Elements

<edges>
    <edge id="e1" source="n1" target="n2" weight="1.0">
        <attvalues>
            <attvalue for="0" value="connects"/>
        </attvalues>
    </edge>
</edges>

Attribute	Required	Description
`id`	No	Unique identifier
`source`	Yes	ID of source node
`target`	Yes	ID of target node
`weight`	No	Edge weight (numeric)
`type`	No	Override default edge type

Complete Example

Here's a complete, valid GEXF file:

<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://www.gexf.net/1.2draft" version="1.2">
    <meta lastmodifieddate="2024-01-15">
        <creator>grph CLI Documentation</creator>
        <description>A simple infrastructure network</description>
    </meta>
    <graph mode="static" defaultedgetype="directed">
        <attributes class="node">
            <attribute id="0" title="type" type="string"/>
            <attribute id="1" title="weight" type="float"/>
        </attributes>
        <attributes class="edge">
            <attribute id="0" title="relationship" type="string"/>
        </attributes>
        <nodes>
            <node id="lb1" label="Load Balancer">
                <attvalues>
                    <attvalue for="0" value="loadbalancer"/>
                    <attvalue for="1" value="0.5"/>
                </attvalues>
            </node>
            <node id="server1" label="Web Server 1">
                <attvalues>
                    <attvalue for="0" value="server"/>
                    <attvalue for="1" value="1.5"/>
                </attvalues>
            </node>
            <node id="db1" label="Database">
                <attvalues>
                    <attvalue for="0" value="database"/>
                    <attvalue for="1" value="3.0"/>
                </attvalues>
            </node>
        </nodes>
        <edges>
            <edge id="e0" source="lb1" target="server1" weight="1.0">
                <attvalues>
                    <attvalue for="0" value="routes"/>
                </attvalues>
            </edge>
            <edge id="e1" source="server1" target="db1" weight="2.0">
                <attvalues>
                    <attvalue for="0" value="queries"/>
                </attvalues>
            </edge>
        </edges>
    </graph>
</gexf>

Common Issues

Namespace Mismatch

grph CLI (via NetworkX) expects specific namespace URLs:

Version	Expected Namespace
1.1	`http://www.gexf.net/1.1draft`
1.2	`http://www.gexf.net/1.2draft`
1.3	`http://gexf.net/1.3`

If your file uses a different namespace URL, you may get a "No <graph> element" error.

Missing Attribute Definitions

If you use attributes on nodes/edges, you must define them first:

<!-- Define attributes BEFORE using them -->
<attributes class="node">
    <attribute id="0" title="type" type="string"/>
</attributes>
<nodes>
    <node id="n1">
        <attvalues>
            <attvalue for="0" value="server"/>  <!-- References id="0" above -->
        </attvalues>
    </node>
</nodes>

Basic Structure​

Elements​

The <gexf> Root Element​

The <meta> Element​

The <graph> Element​

Attribute Definitions​

Node Elements​

Edge Elements​

Complete Example​

Common Issues​

Namespace Mismatch​

Missing Attribute Definitions​

Resources​