Traversals

Traversal functions allow you to explore around the graph and see how vertices are connected.

out / -->

--> or out gets the out adjacent vertices (the functions do exactly the same thing, one just looks cooler). Additionally, a list of labels can be supplied that so that the query only traverses edges with labels in the provided collection. This also applies to the other traversal functions where it makes sense (any function that is named with arrows).

(q/query (g/find-by-id 4)
         q/-->
         q/into-vec!)
;= [#<TinkerVertex v[5]> #<TinkerVertex v[3]>]

(q/query (g/find-by-id 4)
         q/out
         q/into-vec!)
;= [#<TinkerVertex v[5]> #<TinkerVertex v[3]>]

(q/query (g/find-by-id 4)
         (q/--> [:created])
         q/into-vec!)
;= [#<TinkerVertex v[5]> #<TinkerVertex v[3]>]

(q/query (g/find-by-id 4)
         (q/--> [:hates])
         q/into-vec!)
;= []

(q/query (g/find-by-id 4)
         (q/--> [:created :hates])
         q/into-vec!)
;= [#<TinkerVertex v[5]> #<TinkerVertex v[3]>]

out-edges / -E>

Get the outgoing edges of the vertex.

(q/query (g/find-by-id 4)
         q/-E>
         q/into-vec!)
;= [#<TinkerEdge e[10][4-created->5]> #<TinkerEdge e[11][4-created->3]>]

(q/query (g/find-by-id 4)
         q/out-edges
         q/into-vec!)
;= [#<TinkerEdge e[10][4-created->5]> #<TinkerEdge e[11][4-created->3]>]

out-vertex

Get the outgoing tail vertex of the edge.

(q/query (g/find-by-id 4)
         q/-E>
         q/out-vertex
         q/into-vec!)
;= [#<TinkerVertex v[4]> #<TinkerVertex v[4]>]

Conceptually, this might seem same strange at first. Why does it return the same vertex twice? The answer lies in the example queries for -E>. Those queries return two edges. The current query is the same as the -E> query except we are asking for the out-vertex. That means, by the time we are asking for the out-vertex, we have two objects "in the pipeline". Thus, we get two objects back.

in / <--

Get the adjacent vertices pointing to the vertex.

(q/query (g/find-by-id 3)
         q/<--
         q/into-vec!)
;= [#<TinkerVertex v[1]> #<TinkerVertex v[4]> #<TinkerVertex v[6]>]

in-edges / <E-

Get the incoming edges of the vertex.

(q/query (g/find-by-id 3)
         q/<E-
         q/into-vec!)
;= [#<TinkerEdge e[9][1-created->3]> 
;=  #<TinkerEdge e[11][4-created->3]> 
;=  #<TinkerEdge e[12][6-created->3]>]

in-vertex

Get incoming head vertex of the edge.

(q/query (g/find-by-id 3)
         q/<E-
         q/in-vertex
         q/into-vec!)
;= [#<TinkerVertex v[3]> #<TinkerVertex v[3]> #<TinkerVertex v[3]>]

both / <->

Get any vertices that are connected to the given vertex. 

(q/query (g/find-by-id 4)
         q/<->
         q/into-vec!)
;= [#<TinkerVertex v[1]> #<TinkerVertex v[5]> #<TinkerVertex v[3]>]

both-edges / <E>

Get both incoming and outgoing edges of the vertex.

(q/query (g/find-by-id 4)
         q/<E>
         q/into-vec!)
;= [#<TinkerEdge e[8][1-knows->4]> 
;=  #<TinkerEdge e[10][4-created->5]> 
;=  #<TinkerEdge e[11][4-created->3]>]

both-vertices

Get both incoming and outgoing vertices of the edge.

(q/query (g/find-by-id 4)
         q/<E>
         q/both-vertices
         q/into-vec!)
;= [#<TinkerVertex v[1]> #<TinkerVertex v[4]> 
;=  #<TinkerVertex v[4]> #<TinkerVertex v[5]> 
;=  #<TinkerVertex v[4]> #<TinkerVertex v[3]>]

Map like functions are next

You should read about map-like functions next.

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