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Edges
Hermes provides a variety of functions via the hermes.edge namespace
for working with edges.
Given two vertices, a label, and, optionally, a property map,
hermes.edge/connect! creates an edge between the two vertices.
(e/connect! (v/create!) (v/create!) "test-label")
;;#<PersistLabeledTitanEdge e[261:496:1022][496-test-label->500]>
(e/connect! (v/create!) (v/create!) "test-label" {:a 1})
;;#<PersistLabeledTitanEdge e[87:148:326][148-test-label->152]>hermes.edge/endpoints finds the vertices on either side of the edge.
(def edge (e/endpoints (e/connect! (v/create! {:name "start"})
(v/create! {:name "end"}) "test-label")))
;;[#<PersistStandardTitanVertex v[228]> #<PersistStandardTitanVertex v[236]>]
(map v/prop-map edge)
;;({:id 248, :name "start"} {:id 256, :name "end"})Given two vertices, hermes.edge/edges-between returns a set of all
the edges between the two vertices. Optionally, if a label is
provided, then edges-between finds the set of all edges between the
two vertices that have that label.
(def a (v/create!))
;;#'hermes.example/a
(def b (v/create!))
;;#'hermes.example/b
(e/edges-between a b)
;;nil
(e/connect! a b "test-label")
;;#<PersistLabeledTitanEdge e[151:292:326][292-test-label->296]>
(e/edges-between a b)
;;(#<PersistLabeledTitanEdge e[151:292:326][292-test-label->296]>)
(e/connect! a b "test-label")
;;#<PersistLabeledTitanEdge e[153:292:326][292-test-label->296]>
(e/edges-between a b)
;;(#<PersistLabeledTitanEdge e[153:292:326][292-test-label->296]>
#<PersistLabeledTitanEdge e[151:292:326][292-test-label->296]>) Given two vertices, hermes.edge/connected? returns whether the
vertices are connected. Optionally, if a label is provided,
connected? only checks if they are connected by an edge with the
provided label.
(def a (v/create!))
;;#'hermes.example/a
(def b (v/create!))
;;#'hermes.example/b
(e/connected? a b)
;;false
(e/connect! a b "test-label")
;;#<PersistLabeledTitanEdge e[163:316:326][316-test-label->320]>
(e/connected? a b)
;;true
(e/connected? a b "false-label")
;;false hermes.edge/upconnect! takes the idea of an
upsert operation on a object and provides
an analog for edges. Provided two vertices, a label, and, optionally,
a property map, upconnect! will look for all the edges between the
two vertices. If it finds edges and a property map is provided, then
it merges the properties of the map into the properties of all the
discovered edges. If it doesn't find any edges with the given label,
upconnect! will create a edge with that label and the given property
map.
(def a (v/create!))
;;#'hermes.example/a
(def b (v/create!))
;;#'hermes.example/b
(e/edges-between a b)
;;nil
(e/upconnect! a b "test-label" {:a 1})
;;#{#<PersistLabeledTitanEdge e[169:328:326][328-test-label->332]>}
(map v/prop-map (e/edges-between a b))
;;({:id #<RelationIdentifier 169:328:326>, :a 1})
(e/upconnect! a b "test-label" {:b 1})
;;(#<PersistLabeledTitanEdge e[169:328:326][328-test-label->332]>)
(map v/prop-map (e/edges-between a b))
;;({:id #<RelationIdentifier 169:328:326>, :a 1, :b 1})
(e/connect! a b "test-label" {:c 2})
;;#<PersistLabeledTitanEdge e[179:328:326][328-test-label->332]>
(e/upconnect! a b "test-label" {:b 5})
;;(#<PersistLabeledTitanEdge e[179:328:326][328-test-label->332]> #<PersistLabeledTitanEdge e[169:328:326][328-test-label->332]>)
(map v/prop-map (e/edges-between a b))
;;({:id #<RelationIdentifier 179:328:326>, :c 2, :b 5} {:id #<RelationIdentifier 169:328:326>, :a 1, :b 5})