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https://issues.apache.org/jira/browse/FLINK-1815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15382306#comment-15382306
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Greg Hogan commented on FLINK-1815:
-----------------------------------
One area I would like to explore with the next release is storing graphs as
adjacency lists (dependent on FLINK-3695). Depending on if this is successful
and depending on how these are represented, would it be better to read and
write the adjacency list CSV from/to an adjacency list Graph?
{{CsvInputFormat}} uses {{FieldParser}} to convert raw input to the proper
type. I think this is more future-proof than this PR's
{{GraphAdjacencyListReader.fromString}}. I don't know if there are thoughts on
allowing users to register a {{FieldParser}} for a custom type.
I'm not seeing a {{Graph.writeAsCsv}} wrapper around {{DataSet.writeAsCsv}}. If
not implemented this might be nice to add on different ticket.
Thoughts?
> 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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