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neo4jcolorscypher

How to store and find the nearest color in Neo4J using Cypher?

This problem is already solved in How to find the nearest color in SQL but I don't know how to adapt the solution to the Cypher query.

Solution

  • First, you need to convert the color hex into Red, Green, Blue points using this sql. For example; '017fff' is vivid blue

    select CONVERT(int, CONVERT(varbinary, SUBSTRING('017fff', 1, 2), 2)) AS R
        ,CONVERT(int, CONVERT(varbinary, SUBSTRING('017fff', 3, 2), 2)) AS G
        ,CONVERT(int, CONVERT(varbinary, SUBSTRING('017fff', 5, 2), 2)) AS B
UNION ALL
select CONVERT(int, CONVERT(varbinary, SUBSTRING('007ffe', 1, 2), 2)) AS R
        ,CONVERT(int, CONVERT(varbinary, SUBSTRING('007ffe', 3, 2), 2)) AS G
        ,CONVERT(int, CONVERT(varbinary, SUBSTRING('007ffe', 5, 2), 2)) AS B
UNION ALL
select CONVERT(int, CONVERT(varbinary, SUBSTRING('007fff', 1, 2), 2)) AS R
        ,CONVERT(int, CONVERT(varbinary, SUBSTRING('007fff', 3, 2), 2)) AS G
        ,CONVERT(int, CONVERT(varbinary, SUBSTRING('007fff', 5, 2), 2)) AS B
    Red Green Blue
    1 127 255
    0 127 254
    0 127 255

    Secondly, create the nodes in neo4j using Spatial function (3D). https://neo4j.com/docs/cypher-manual/current/functions/spatial/#functions-point-cartesian-3d

    For example:

    CREATE (:Color {coor: point({x: 1, y: 127, z: 255})})    //vivid blue
CREATE (:Color {coor: point({x: 0, y: 127, z: 254})})    //mostly pure blue
CREATE (:Color {coor: point({x: 0, y: 127, z: 255})})    //pure blue

    enter image description here

    Lastly, to calculate the distance (or closest distance), use this function. https://neo4j.com/docs/cypher-manual/current/functions/spatial/#functions-distance

    For example:

    MATCH (n:Color {coor: point({x:1, y:127, z:255})}), (m:Color)
WITH n, m, point.distance(m.coor, n.coor) as dist WHERE n <> m
RETURN n, m, dist ORDER by dist LIMIT 1

    Answer: Pure blue is closest to vivid blue

    ╒══════════════════════════════════════════════╤══════════════════════════════════════════════╤══════╕
│"given_color"                                 │"closest_color"                               │"dist"│
╞══════════════════════════════════════════════╪══════════════════════════════════════════════╪══════╡
│{"coor":point({srid:9157, x:1, y:127, z:255})}│{"coor":point({srid:9157, x:0, y:127, z:255})}│1.0   │
└──────────────────────────────────────────────┴──────────────────────────────────────────────┴──────┘