[50/50] [abbrv] tinkerpop git commit: translated shortest path recipes into their respective OLAP version using the new shortestPath() step

[dk...@apache.org]

translated shortest path recipes into their respective OLAP version using the new shortestPath() step


Project: http://git-wip-us.apache.org/repos/asf/tinkerpop/repo
Commit: http://git-wip-us.apache.org/repos/asf/tinkerpop/commit/d8a3626f
Tree: http://git-wip-us.apache.org/repos/asf/tinkerpop/tree/d8a3626f
Diff: http://git-wip-us.apache.org/repos/asf/tinkerpop/diff/d8a3626f

Branch: refs/heads/TINKERPOP-1990
Commit: d8a3626fd54d3e3bb2d883d090c9e289374591ea
Parents: 362ed16
Author: Daniel Kuppitz <da...@hotmail.com>
Authored: Tue Jul 31 10:58:09 2018 -0700
Committer: Daniel Kuppitz <da...@hotmail.com>
Committed: Wed Aug 1 12:29:06 2018 -0700

----------------------------------------------------------------------
 docs/src/recipes/shortest-path.asciidoc         | 63 ++++++++++++++++++++
 .../Process/Traversal/GraphTraversal.cs         |  2 +-
 2 files changed, 64 insertions(+), 1 deletion(-)
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http://git-wip-us.apache.org/repos/asf/tinkerpop/blob/d8a3626f/docs/src/recipes/shortest-path.asciidoc
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diff --git a/docs/src/recipes/shortest-path.asciidoc b/docs/src/recipes/shortest-path.asciidoc
index 2e33055..e25d777 100644
--- a/docs/src/recipes/shortest-path.asciidoc
+++ b/docs/src/recipes/shortest-path.asciidoc
@@ -48,6 +48,17 @@ course, it is possible for there to be more than one path in the graph of the sa
 length three), but this example is not considering that.
 <2> It might be interesting to know the path lengths for all paths between vertex "1" and "5".
 <3> Alternatively, one might wish to do a path length distribution over all the paths.
+<4> The preferred way to get a shortest path in OLAP is the `shortestPath()` step.
+
+The following code block demonstrates how the shortest path from `v[1]` to `v[5]` can be queried in OLAP, using the `shortestPath()` step.
+
+[gremlin-groovy,existing]
+----
+g = g.withComputer()
+g.V(1).shortestPath().
+  with(ShortestPath.edges, Direction.OUT).
+  with(ShortestPath.target, hasId(5))
+----
 
 The previous example defines the length of the path by the number of vertices in the path, but the "path" might also
 be measured by data within the graph itself. The following example use the same graph structure as the previous example,
@@ -95,6 +106,17 @@ calculated cost. With some slight modifications given the use of `select` it bec
 the output. Note that the path with the lowest "cost" actually has a longer path length as determined by the graph
 structure.
 
+The next code block demonstrates how the `shortestPath()` step can be used in OLAP to determine the shortest weighted path.
+
+[gremlin-groovy,existing]
+----
+g = g.withComputer()
+g.V(1).shortestPath().
+  with(ShortestPath.edges, Direction.OUT).
+  with(ShortestPath.distance, 'weight').
+  with(ShortestPath.target, hasId(5))
+----
+
 The following query illustrates how `select(<traversal>)` can be used to find all shortest weighted undirected paths
 in the modern toy graph.
 
@@ -136,3 +158,44 @@ g.withSack(0.0).V().as("from").       <1>
 <7> Order the output by the start vertex id and then the end vertex id (for better readability).
 <8> Deduplicate vertex pairs (the shortest path from `v[1]` to `v[6]` is the same as the path from `v[6]` to `v[1]`).
 
+Again, this can be translated into an OLAP query using the `shortestPath()` step.
+
+[gremlin-groovy,existing]
+----
+result = g.withComputer().V().
+  shortestPath().
+    with(ShortestPath.distance, 'weight').
+    with(ShortestPath.includeEdges, true).
+  filter(count(local).is(gt(1))).
+  group().
+    by(project('from','to').
+         by(limit(local, 1)).
+         by(tail(local, 1))).
+  unfold().
+  order().
+    by(select(keys).select('from').id()).
+    by(select(keys).select('to').id()).toList()
+----
+
+The obvious difference in the result is the absence of property values in the OLAP result. Since OLAP traversers are not
+allowed to leave the local star graph, it's not possible to have the exact same result in an OLAP query. However, the determined
+shortest paths can be passed back into the OLTP `GraphTraversalSource`, which can then be used to query the values.
+
+[gremlin-groovy,existing]
+----
+g.withSideEffect('v', []).                            <1>
+  inject(result.toArray()).as('kv').select(values).
+  unfold().
+  map(unfold().as('v_or_e').
+      coalesce(V().where(eq('v_or_e')).store('v'),
+               select('v').tail(local, 1).bothE().where(eq('v_or_e'))).
+      values('name','weight').
+      fold()).
+  group().
+    by(select('kv').select(keys)).unfold().
+  order().
+    by(select(keys).select('from').id()).
+    by(select(keys).select('to').id()).toList()
+----
+
+<1> The side-effect `v` is used to keep track of the last processed vertex, hence it needs to be an order-preserving list. Without this explicit definition `v` would become a `BulkSet` which doesn't preserve the insert order.

http://git-wip-us.apache.org/repos/asf/tinkerpop/blob/d8a3626f/gremlin-dotnet/src/Gremlin.Net/Process/Traversal/GraphTraversal.cs
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diff --git a/gremlin-dotnet/src/Gremlin.Net/Process/Traversal/GraphTraversal.cs b/gremlin-dotnet/src/Gremlin.Net/Process/Traversal/GraphTraversal.cs
index aba8a7f..af78f20 100644
--- a/gremlin-dotnet/src/Gremlin.Net/Process/Traversal/GraphTraversal.cs
+++ b/gremlin-dotnet/src/Gremlin.Net/Process/Traversal/GraphTraversal.cs
@@ -1731,4 +1731,4 @@ namespace Gremlin.Net.Process.Traversal
         }
 
     }
-}
+}
\ No newline at end of file