How do I write a for loop in gremlin? This is what I tried:
for i=0;i<10:i++:println hello number i
I also tried to iterate over nodes and call a function on each one e.g.(count):
gremlin> g.v(782).in==> v[2746934]
==> v[2581232]
==> v[1554286]
==> v[780]
gremlin> g.v(78).in.loop(2){it.loops < 4}.count()
==> class java.lang.NullPointerException : null
My main aim is to execute a for loop and print the value of nodes that have no inE. Which means the in degree of them is zero.
If you want to iterate over all the nodes in the graph to get a count of how many didn't have in edges you could do something like:
gremlin> g = TinkerGraphFactory.createTinkerGraph()
==>tinkergraph[vertices:6 edges:6]
gremlin> g.V.filter{!it.inE.hasNext()}.count()
==>2
If you want to perform some side-effect like doing a "print", then use the side-effect step:
gremlin> g.V.filter{!it.inE.hasNext()}.sideEffect{println it.name}
marko
==>v[1]
peter
==>v[6]
Note that it's printing twice because the Gremlin terminal is already printing for you, so if you're in the terminal you might as well just do:
gremlin> g.V.filter{!it.inE.hasNext()}.name
==>marko
==>peter
filter{!it.inE.hasNext()} is more efficient as a full count/iteration is not required.