Imported node and edge IDs are overwritten.

Question

Hello,

when I import a self-written GML file to yEd, and then apply an auto-layout routine (hierarchical) on my graph, the IDs of my nodes and edges are overwritten. Is this a bug or intented behavior? I would prefer my IDs to stay as they were at the time of import, as I might want to use them again.

Answer 1

Short answer: This is the intended behavior.

Long answer: GML and GraphML IDs are format-specific "implementation detail". These IDs are only used during serialization/deserialization process itself and are *not* stored in the in-memory graph structure. E.g. if you create a graph, then save to GML/GraphML and then save the *same* graph again to GML/GraphML, the serializer is allowed to generate completely different IDs.

If you need IDs for your graph elements, add custom ID properties to the nodes and edges ("Edit" -> "Manage Custom Properties") and store your graph in the GraphML format. (yEd does not support custom properties for GML.)