GEXF

GEXF static graphs. Advantage over GraphML: a native <viz:position> element for node x/y, and a real liststring type for arrays. Knotviz doesn’t validate the version attribute, so any GEXF file that matches the structure below will load.

Minimum viable example

graph.gexf

<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://gexf.net/1.3" xmlns:viz="http://gexf.net/1.3/viz" version="1.3">
  <graph mode="static" defaultedgetype="directed">
    <attributes class="node">
      <attribute id="0" title="age" type="integer"/>
      <attribute id="1" title="tags" type="liststring"/>
    </attributes>
    <nodes>
      <node id="n1" label="Alice">
        <attvalues>
          <attvalue for="0" value="34"/>
          <attvalue for="1" value="engineer|founder"/>
        </attvalues>
        <viz:position x="10" y="20"/>
      </node>
      <node id="n2" label="Bob"/>
    </nodes>
    <edges>
      <edge source="n1" target="n2" weight="0.8"/>
    </edges>
  </graph>
</gexf>

Download example

Supported attribute types

type	Maps to	Note
integer, long, float, double	number	Range/precision not checked — all become JS numbers.
boolean	boolean	"true" / "false" (case-insensitive) and "1" / "0".
string, anyURI	string	Promoted to date if every value is ISO 8601 (see below).
liststring	string[]	Pipe-delimited. | escapes a literal pipe; \\ escapes a literal backslash.

Dates in GEXF

GEXF has no native date type. Declare the column as type="string" with ISO-8601 values and Knotviz will re-classify it to date after parse — you get a date picker in filters and a timeline gradient in Analyze.

<attribute id="2" title="joined" type="string"/>
...
<attvalue for="2" value="2021-03-15"/>

If even one value doesn’t match ISO 8601, the column stays string.

Opting out. To keep an ISO-looking value as a plain string (e.g. a version tag), re-shape it so it doesn’t match the regex: v2021-03-15, 20210315, ver:2021-03-15.

Structural mappings

GEXF element / attribute	Becomes	Note
<node id="…">	NodeInput.id	Required.
<node label="…">	NodeInput.label	Display text, read from the element attribute.
<viz:position x="…" y="…"/>	NodeInput.x / .y	z is ignored. Positions rules apply.
<attvalues> on node	Node properties	Typed per the matching <attribute> declaration.
<edge weight="…">	EdgeInput.weight	Numeric. Read from the element attribute; if missing, falls back to an <attvalue> on the edge titled weight.
Any other edge <attvalue>	Dropped	Knotviz edges only carry weight.

Coming from another tool

Gephi

File → Export → Graph File → .gexf. Tick Export positions if you want the layout preserved (Knotviz reads viz:position automatically). Untick Export visual config — viz:color / viz:size / viz:shape are ignored on our side and just bloat the file.

NetworkX

nx_to_gexf.py

import networkx as nx
nx.write_gexf(G, "graph.gexf")

NetworkX defaults to GEXF 1.2. Knotviz was written against the 1.3 spec but doesn’t check the version declaration, so 1.2 files load fine in practice — the element names and attribute shapes Knotviz reads are the same in both.

ForceAtlas2 / Gephi round-trip

If you’ve run Gephi’s ForceAtlas2 layout and want to preserve it, export as .gexf — positions ride inside <viz:position>. Knotviz uses them as the initial layout; press Space only if you want to re-simulate.

GEXF or GraphML?

• Positions. If you need to preserve x/y end-to-end, use GEXF. GraphML has no standard position element.
• Arrays. If you need real string[] properties, use GEXF (liststring). GraphML can only carry them as pipe-delimited strings that stay string.
• Portability. More graph tools read and write GraphML than GEXF. If interop matters more than positions/arrays, use GraphML.
• File size. GEXF’s XML is slightly more verbose; 10–20% bigger at comparable fidelity.

Gotchas

• Dynamic mode / <spells> elements are ignored. Knotviz reads GEXF as static only.
• Visual styling is ignored. viz:color, viz:size, viz:shape parse cleanly but don’t render. Use Knotviz’s Analyze panel for colour and size.
• Edges can’t carry arbitrary data. Only weight transfers; other <attvalue> entries on edges are dropped.
• Namespaces are stripped. The parser normalises prefixed elements (<gexf:node> → <node>) before matching, so you can use any namespace prefix without affecting the load.
• Silent skips land in the console. Unknown <attvalue for="…"> references, edges to unknown node ids, and nodes without an id all fall through with a console.warn. Open devtools if a count looks off.
• No streaming parser. Files above ~1M nodes may OOM a 4 GB browser tab — see limits for the hard ceiling.
• UTF-8 recommended. No explicit BOM handling. If a file that looks fine errors with “Malformed GEXF XML”, save without the BOM.