[FLINK-1758] Extend Gelly's neighborhood methods

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Implemented
• Affects Version/s: 0.9
• Fix Version/s: 0.9
• Component/s: Library / Graph Processing
• Assignee: Andra Lungu
• Reporter: Vasia Kalavri
• Created: 20/Mar/15 13:13
• Updated: 26/Apr/15 12:33
• Resolved: 26/Apr/15 12:33

Description

Currently, the neighborhood methods only allow returning a single value per vertex. In many cases, it is desirable to return several or no value per vertex. This is the case in clustering coefficient computation, vertex-centric jaccard, algorithms where a vertex computes a value per edge or when a vertex computes a value only for some of its neighbors.

This issue proposes to

• change the current reduceOnEdges/reduceOnNeighbors methods to use combinable reduce operations where possible
• provide groupReduce-versions, which will use a Collector and allow returning none or more values per vertex.