Github user okram commented on a diff in the pull request: https://github.com/apache/tinkerpop/pull/531#discussion_r95563597 --- Diff: docs/src/recipes/appendix.asciidoc --- @@ -0,0 +1,226 @@ +//// +Licensed to the Apache Software Foundation (ASF) under one or more +contributor license agreements. See the NOTICE file distributed with +this work for additional information regarding copyright ownership. +The ASF licenses this file to You under the Apache License, Version 2.0 +(the "License"); you may not use this file except in compliance with +the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +//// +Appendix +======== + +Many of the recipes are based on questions and answers provided on the gremlin-users mailing list. This section +contains a number of traversals from the mailing list that do not easily fit any particular pattern (i.e. a recipe), +but are nonetheless interesting and thus remain good tools for learning Gremlin. + +[[appendix-a]] +_For each person in a "follows" graph, determine the number of followers and list their names._ + +[gremlin-groovy] +---- +g.addV('name','marko').as('marko'). + addV('name','josh').as('josh'). + addV('name','daniel').as('daniel'). + addV('name','matthias').as('matthias'). + addE('follows').from('josh').to('marko'). + addE('follows').from('matthias').to('josh'). + addE('follows').from('daniel').to('josh'). + addE('follows').from('daniel').to('marko').iterate() +g.V().as('p'). + map(__.in('follows').values('name').fold()). + group().by(select('p').by('name')). + by(project('numFollowers','followers'). + by(count(local)).by()).next() +---- + +[[appendix-b]] +_In the "modern" graph, show each person, the software they worked on and the co-worker count for the software and +the names of those co-workers._ + +[gremlin-groovy,modern] +---- +g.V().hasLabel("person").as("p"). + out("created").as("s"). + map(__.in("created"). + where(neq("p")).values("name").fold()). + group().by(select("p").by("name")). + by(group().by(select("s").by("name")). + by(project("numCoworkers","coworkers"). + by(count(local)).by())).next() +---- + +[[appendix-c]] +_Assuming a graph of students, classes and times, detect students who have a conflicting schedule._ + +[gremlin-groovy] +---- +g.addV(label, "student", "name", "Pete").as("s1"). + addV(label, "student", "name", "Joe").as("s2"). + addV(label, "class", "name", "Java's GC").as("c1"). + addV(label, "class", "name", "FP Principles").as("c2"). + addV(label, "class", "name", "Memory Management in C").as("c3"). + addV(label, "class", "name", "Memory Management in C++").as("c4"). + addV(label, "timeslot", "date", "11/25/2016", "fromTime", "10:00", "toTime", "11:00").as("t1"). + addV(label, "timeslot", "date", "11/25/2016", "fromTime", "11:00", "toTime", "12:00").as("t2"). + addE("attends").from("s1").to("c1"). + addE("attends").from("s1").to("c2"). + addE("attends").from("s1").to("c3"). + addE("attends").from("s1").to("c4"). + addE("attends").from("s2").to("c2"). + addE("attends").from("s2").to("c3"). + addE("allocated").from("c1").to("t1"). + addE("allocated").from("c1").to("t2"). + addE("allocated").from("c2").to("t1"). + addE("allocated").from("c3").to("t2"). + addE("allocated").from("c4").to("t2").iterate() +g.V().hasLabel("student").as("s"). + out("attends").as("c"). + out("allocated").as("t"). + select("s"). + out("attends"). + where(neq("c")). + out("allocated"). + where(eq("t")). + group(). + by(select("s").by("name")). + by(group().by(select("t").by(valueMap("fromTime","toTime"))). + by(select("c").dedup().values("name").fold())).next() +---- + +[[appendix-d]] +_In the "modern" graph, with a duplicate edge added, find the vertex pairs that have more than one edge between them._ + +[gremlin-groovy,modern] +---- +g.V(1).as("a").V(3).addE("created").property("weight",0.4d).from("a").iterate() +g.V(1).outE("created") +g.V().as("a"). + out().as("b"). + groupCount(). + by(select("a","b")). + unfold(). + filter(select(values).is(gt(1))). + select(keys) +---- + +[[appendix-e]] +_In the "crew" graph, find vertices that match on a complete set of multi-properties._ + +[gremlin-groovy,theCrew] +---- +places = ["centreville","dulles"];[] // will not match as "purcellville" is missing +g.V().not(has("location", without(places))). + where(values("location").is(within(places)).count().is(places.size())). + valueMap() +places = ["centreville","dulles","purcellville"];[] +g.V().not(has("location", without(places))). + where(values("location").is(within(places)).count().is(places.size())). + valueMap() +---- + +[[appendix-f]] +_Methods for performing some basic mathematical operations in the "modern" graph._ + +[gremlin-groovy,modern] +---- +g.V().values("age").sum() // sum all ages +g.V().values("age").fold(1, mult) // multiply all ages +g.V().values("age").map(union(identity(), constant(-1)).sum()) // subtract 1 +g.V().values("age").map(union(identity(), identity()).sum()) // multiply by 2 (simple) +g.V().values("age").map(union(identity(), constant(2)).fold(1, mult)) // multiply by 2 (generally useful for multiplications by n): +---- + +[[appendix-g]] +_Dropping a vertex, as well as the vertices related to that dropped vertex that are connected by a "knows" edge in the +"modern" graph_ + +[gremlin-groovy,modern] +---- +g.V().has('name','marko').outE() +g.V().has('name','marko').sideEffect(out('knows').drop()).drop() +g.V().has('name','marko') +g.V(2,4,3) +---- + +[[appendix-h]] +_For the specified graph, find all neighbor vertices connected to "A" as filtered by datetime, those neighbor vertices +that don't have datetime vertices, and those neighbor vertices that have the label "dimon"._ + +[gremlin-groovy] +---- +g.addV().property("name", "A").as("a"). + addV().property("name", "B").as("b"). + addV().property("name", "C").as("c"). + addV().property("name", "D").as("d"). + addV().property("name", "E").as("e"). + addV("dimon").property("name", "F").as("f"). + addV().property("name", "G").as("g").property("date", 20160818). + addV().property("name", "H").as("h").property("date", 20160817). + addE("rel").from("a").to("b"). + addE("rel").from("a").to("c"). + addE("rel").from("a").to("d"). + addE("rel").from("a").to("e"). + addE("rel").from("c").to("f"). + addE("occured_at").from("d").to("g"). + addE("occured_at").from("e").to("h").iterate() +// D and E have a valid datetime +g.V().has("name", "A").out("rel"). + union(where(out("occured_at").has("date", gte(20160817))), + __.not(outE("occured_at")).coalesce(out().hasLabel("dimon"), identity())). + valueMap() +// only E has a valid date +g.V().has("name", "A").out("rel"). + union(where(out("occured_at").has("date", lte(20160817))), + __.not(outE("occured_at")).coalesce(out().hasLabel("dimon"), identity())). + valueMap() +// only D has a valid date +g.V().has("name", "A").out("rel"). + union(where(out("occured_at").has("date", gt(20160817))), + __.not(outE("occured_at")).coalesce(out().hasLabel("dimon"), identity())). + valueMap() +// neither D nor E have a valid date +g.V().has("name", "A").out("rel"). + union(where(out("occured_at").has("date", lt(20160817))), + __.not(outE("occured_at")).coalesce(out().hasLabel("dimon"), identity())). + valueMap() +---- + +[[appendix-i]] +_Use element labels in a `select`._ + +[gremlin-groovy,modern] +---- +g.V(1).as("a"). + both(). + map(group().by(label).by(unfold())).as("b"). + select("a","b"). + map(union(project("a").by(select("a")), select("b")). + unfold(). + group(). + by(select(keys)). + by(select(values))) +g.V().as("a"). + both(). + map(group().by(label).by(unfold())).as("b"). + select("a","b"). + group(). + by(select("a")). + by(select("b"). + group(). + by(select(keys)). + by(select(values).fold())). + unfold(). + map(union(select(keys).project("a").by(), select(values)). + unfold(). + group(). + by(select(keys).unfold()). + by(select(values).unfold().unfold().fold())) +---- --- End diff -- I'm wondering if some of these traversals may "look better" with `match()`. @dkuppitz ?
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