Hi everyone, We are gonna start with a brief explanation about topic. Gremlin is the graph traversal language of Apache TinkerPop. It is a functional, data-flow language that enables users to succinctly express complex traversals on (or queries of) their application’s property graph.
After installation from this website ,start the gremlin console.
Creating a Graph
This is our graph which is we are gonna build. First of all we create our nodes.
graph = TinkerGraph.open()
v1=graph.addVertex(T.id,1,T.label,"person","personId","p4361","name","Jonny Deep")
v2=graph.addVertex(T.id,2,T.label,"user","userId","u185","age",12,"gender","M")
v3=graph.addVertex(T.id,3,T.label,"user","userId","u75","age",17,"gender","F")
v4=graph.addVertex(T.id,4,T.label,"movie","movieId","m267","title","Alice in Wonderland","year",2010,"duration","108","country","US")
v5=graph.addVertex(T.id,5,T.label,"genre","genreId","g2","name","Adventure")
v6=graph.addVertex(T.id,6,T.label,"movie","movieId","m16","title","Alice in Wonderland","year",1951,"duration","75","country","US")
Now, we build their edges.
v4.addEdge("actor",v1,"id",7)
v4.addEdge("belongsTo",v5,"id",8)
v2.addEdge("rated",v4,"id",9,"rating",5)
v2.addEdge("rated",v6,"id",10,"rating",6)
v6.addEdge("belongsTo",v5,"id",11)
v3.addEdge("knows",v2,"id",12)
Graph Traversal
We use graph traversal if we want to draw a desired property of the node.
g=graph.traversal()
g.V().has("title","Alice in Wonderland").has("year",2010).out("actor").values("name")
values(“age”) take the age values for us. If “values()” is not added at the end ,only the nodes and their numbers will be printed
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mean(): averaging
g.V().has("gender",within("F","M")).values("age")
g.V().has("gender",within("F","M")).values("age").mean()
g.V().has("gender",within("F","M"))
in() & out()
g.V().has("country","US").in("rated").values("age")
g.V().has("gender","M").out("rated").values("title","year")
We can group them according to the feature we choose.
g.V().group().by(label)
In the next part of our series, we will continue with expanding our graph.
We’ll add 2 more vertex and edges.
v7=graph.addVertex(T.id,13,T.label,"person","personId","p5206","name","Linda Woolverton")
v8=graph.addVertex(T.id,14,T.label,"person","personId","p8153","name","Tim Burton")
v4.addEdge("screenwriter",v7,"id",15)
v4.addEdge("director",v8,"id",16)
If we want to learn the name of the director of the movie Alice in Wonderland, which was released in 2010.
(==>Tim Burton)
g.V().has("title","Alice in Wonderland").has("year",2010).out("director").values("name")If we want the names of both director and screenwriter, we just need to add “screenwriter”.
(==>Tim Burton
==>Linda Woolverton)
g.V().has("title","Alice in Wonderland").has("year",2010).out("director","screenwriter").values("name")
Note: If you wanna learn more about tinkerpop, I recommend you check out this YouTube video and tinkerpop tutorial.
https://kelvinlawrence.net/book/Gremlin-Graph-Guide.html#gremlininstall
