14.5.5 Advanced Multi-Edge Handling
Both simplify() and undirect() support the removal of multi-edges using MultiEdges.REMOVE_MULTI_EDGES. If this parameter is set, all multi-edges in this graph are removed, that is, collapsed. Whenever several multi-edges with edge properties are collapsed into one edge, you can choose one of the following two strategies supported by the graph server (PGX) to decide how to treat the corresponding properties:
- Picking
- Merging
If you choose picking, the graph server (PGX) picks one edge out of every set of multi-edges and copies all its properties including the edge label and key into the new graph. In the case of merging, the graph server (PGX) creates a completely new edge out for every set of multi-edges. PGX determines the properties of these new edges by applying a MergingFunction on every property of the multi-edges.
If there are no multi-edges between two vertices, that is, zero or only one edge, the chosen strategy does not have an effect on the outcome. The edge is kept with all its properties as it is.
Parent topic: Graph Mutation and Subgraphs