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https://issues.apache.org/jira/browse/FLINK-1815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15536006#comment-15536006
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Greg Hogan commented on FLINK-1815:
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Questions:
- It feels like we're making up our own format (as opposed to something common
like CSV), is there data stored in this adjacency list format? Is this better
than storing separate CSV files for the vertex and edge sets? Writing the graph
in this form requires a cogroup and reading often requires parsing the file
twice.
- Performance of string splits and concatenations.
- Flexibility and performance of {{GraphAdjacencyListReader.fromString()}}
compared with using {{FieldParser}}'s.
> Add methods to read and write a Graph as adjacency list
> -------------------------------------------------------
>
> Key: FLINK-1815
> URL: https://issues.apache.org/jira/browse/FLINK-1815
> Project: Flink
> Issue Type: New Feature
> Components: Gelly
> Affects Versions: 0.9
> Reporter: Vasia Kalavri
> Assignee: Faye Beligianni
> Priority: Minor
>
> It would be nice to add utility methods to read a graph from an Adjacency
> list format and also write a graph in such a format.
> The simple case would be to read a graph with no vertex or edge values, where
> we would need to define (a) a line delimiter, (b) a delimiter to separate
> vertices from neighbor list and (c) and a delimiter to separate the neighbors.
> For example, "1 2,3,4\n2 1,3" would give vertex 1 with neighbors 2, 3 and 4
> and vertex 2 with neighbors 1 and 3.
> If we have vertex values and/or edge values, we also need to have a way to
> separate IDs from values. For example, we could have "1 0.1 2 0.5, 3 0.2" to
> define a vertex 1 with value 0.1, edge (1, 2) with weight 0.5 and edge (1, 3)
> with weight 0.2.
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