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From: spmallette@apache.org
To: commits@tinkerpop.apache.org
Message-Id: <5f896cf9e04b4ffe8fef3c98bf069cdf@git.apache.org>
Subject: tinkerpop git commit: Added some notes on sampling to recommendation
 recipe CTR
Date: Thu,  9 Mar 2017 12:35:43 +0000 (UTC)
archived-at: Thu, 09 Mar 2017 12:35:45 -0000

Repository: tinkerpop
Updated Branches:
  refs/heads/tp32 df285d380 -> 3fe223bdc


Added some notes on sampling to recommendation recipe CTR


Project: http://git-wip-us.apache.org/repos/asf/tinkerpop/repo
Commit: http://git-wip-us.apache.org/repos/asf/tinkerpop/commit/3fe223bd
Tree: http://git-wip-us.apache.org/repos/asf/tinkerpop/tree/3fe223bd
Diff: http://git-wip-us.apache.org/repos/asf/tinkerpop/diff/3fe223bd

Branch: refs/heads/tp32
Commit: 3fe223bdcbf0695529aa9f5fd58b3bff573845b6
Parents: df285d3
Author: Stephen Mallette <spmva@genoprime.com>
Authored: Thu Mar 9 07:34:23 2017 -0500
Committer: Stephen Mallette <spmva@genoprime.com>
Committed: Thu Mar 9 07:34:23 2017 -0500

----------------------------------------------------------------------
 docs/src/recipes/recommendation.asciidoc | 45 ++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/tinkerpop/blob/3fe223bd/docs/src/recipes/recommendation.asciidoc
----------------------------------------------------------------------
diff --git a/docs/src/recipes/recommendation.asciidoc b/docs/src/recipes/recommendation.asciidoc
index 8d5f1ec..0aaa7e4 100644
--- a/docs/src/recipes/recommendation.asciidoc
+++ b/docs/src/recipes/recommendation.asciidoc
@@ -245,4 +245,47 @@ g.V().has("person","name","alice").as("alice").
         by(values, decr).
         by(select(keys).values("name")).
       unfold().select(keys).values("name")
-----
\ No newline at end of file
+----
+
+In considering the practical applications of this recipe, it is worth revisiting the earlier "basic" version of the
+reccomendation algorithm:
+
+[gremlin-groovy,existing]
+----
+g.V().has('person','name','alice').as('her').
+      out('bought').aggregate('self').
+      in('bought').where(neq('her')).
+      out('bought').where(without('self')).
+      groupCount().
+      order(local).
+        by(values, decr)
+----
+
+The above traversal performs a full ranking of items based on all the connected data. That could be a time consuming
+operation depending on the number of paths being traversed. As it turns out, recommendations don't need to have perfect
+knowledge of all data to provide a "pretty good" approximation of a recommendation. It can therefore make sense to
+place additional limits on the traversal to have it better return more quickly at the expense of examining less data.
+
+
+Gremlin provides a number of steps that can help with these limits like:
+link:http://tinkerpop.apache.org/docs/x.y.z/reference/#coin-step[coin()],
+link:http://tinkerpop.apache.org/docs/x.y.z/reference/#sample-step[sample()], and
+link:http://tinkerpop.apache.org/docs/current/reference/#timelimit-step[timeLimit()]. For example, to have the
+traversal sample the data for no longer than one second, the previous "basic" recommendation could be changed to:
+
+[gremlin-groovy,existing]
+----
+g.V().has('person','name','alice').as('her').
+      out('bought').aggregate('self').
+      in('bought').where(neq('her')).
+      out('bought').where(without('self')).timeLimit(1000).
+      groupCount().
+      order(local).
+        by(values, decr)
+----
+
+In using sampling methods, it is important to consider that the natural ordering of edges in the graph may not produce
+an ideal sample for the recommendation. For example, if the edges end up being returned oldest first, then the
+recommendation will be based on the oldest data, which would not be ideal. As with any traversal, it is important to
+understand the nature of the graph being traversed and the behavior of the underlying graph database to properly
+achieve the desired outcome.
\ No newline at end of file