Dijkstra algorithm in Neo4j with example

cities.md

Adding nodes and relationships to DB

CREATE (Rotterdam:City {title:'Rotterdam'})
CREATE (DenHaag:City {title:'Den Haag'})
CREATE (Leiden:City {title:'Leiden'})
CREATE (Delft:City {title:'Delft'})
CREATE (Amsterdam:City {title:'Amsterdam'})
CREATE (Utrecht:City {title:'Utrecht'})
CREATE (Arnhem:City {title:'Arnhem'})
CREATE (Groningen:City {title:'Groningen'})
CREATE (Maastricht:City {title:'Maastricht'})
CREATE (DenBosch:City {title:'Den Bosch'})
CREATE (Tilburg:City {title:'Tilburg'})

CREATE
  (Utrecht)-[:NEIGHBOUR {weight:6}]->(Rotterdam),
  (Utrecht)-[:NEIGHBOUR {weight:7}]->(DenHaag),
  (Utrecht)-[:NEIGHBOUR {weight:8}]->(Leiden),
  (Utrecht)-[:NEIGHBOUR {weight:6}]->(Tilburg),
  (Utrecht)-[:NEIGHBOUR {weight:9}]->(Arnhem),
  (Rotterdam)-[:NEIGHBOUR {weight:4}]->(DenHaag),
  (Rotterdam)-[:NEIGHBOUR {weight:2}]->(Delft),
  (Rotterdam)-[:NEIGHBOUR {weight:7}]->(DenBosch),
  (DenHaag)-[:NEIGHBOUR {weight:2}]->(Leiden),
  (DenHaag)-[:NEIGHBOUR {weight:2}]->(Delft),
  (DenHaag)-[:NEIGHBOUR {weight:4}]->(Amsterdam),
  (Leiden)-[:NEIGHBOUR {weight:3}]->(Amsterdam),
  (Arnhem)-[:NEIGHBOUR {weight:11}]->(Groningen),
  (Arnhem)-[:NEIGHBOUR {weight:8}]->(Tilburg),
  (Arnhem)-[:NEIGHBOUR {weight:10}]->(Maastricht),
  (Tilburg)-[:NEIGHBOUR {weight:4}]->(DenBosch),
  (Tilburg)-[:NEIGHBOUR {weight:5}]->(Maastricht)

##Shortest path using Dijkstra algorithm

Send request to http://localhost:7474/db/data/node/{node_id}/paths where node_id is the node id of the city.

Use these headers:

Accept: application/json; charset=UTF-8
Content-Type: application/json

And insert this into the body:

{
  "to": "http://localhost:7474/db/data/node/{node_id}",
  "cost_property": "weight",
  "relationships" : {
    "type": "NEIGHBOUR"
  },
  "algorithm": "dijkstra"
}

Where node_id is the node id of which city you want to go to.

The DB will respond with something like this:

[
  {
      "weight": 15,
      "start": "http://localhost:7474/db/data/node/175",
      "nodes": [
          "http://localhost:7474/db/data/node/175",
          "http://localhost:7474/db/data/node/172",
          "http://localhost:7474/db/data/node/171",
          "http://localhost:7474/db/data/node/180"
      ],
      "length": 3,
      "relationships": [
          "http://localhost:7474/db/data/relationship/263",
          "http://localhost:7474/db/data/relationship/258",
          "http://localhost:7474/db/data/relationship/260"
      ],
      "end": "http://localhost:7474/db/data/node/180"
  },
  {
      "weight": 15,
      "start": "http://localhost:7474/db/data/node/175",
      "nodes": [
          "http://localhost:7474/db/data/node/175",
          "http://localhost:7474/db/data/node/172",
          "http://localhost:7474/db/data/node/174",
          "http://localhost:7474/db/data/node/171",
          "http://localhost:7474/db/data/node/180"
      ],
      "length": 4,
      "relationships": [
          "http://localhost:7474/db/data/relationship/263",
          "http://localhost:7474/db/data/relationship/262",
          "http://localhost:7474/db/data/relationship/259",
          "http://localhost:7474/db/data/relationship/260"
      ],
      "end": "http://localhost:7474/db/data/node/180"
  }
]

The top element in the array is the shortest path with least steps.