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From "Marko A. Rodriguez (JIRA)" <j...@apache.org>
Subject [jira] [Created] (TINKERPOP3-798) [Proposal] Rename mapKeys()/mapValues() to select(keys) and select(values).
Date Tue, 04 Aug 2015 18:24:04 GMT
Marko A. Rodriguez created TINKERPOP3-798:
---------------------------------------------

             Summary: [Proposal] Rename mapKeys()/mapValues() to select(keys) and select(values).
                 Key: TINKERPOP3-798
                 URL: https://issues.apache.org/jira/browse/TINKERPOP3-798
             Project: TinkerPop 3
          Issue Type: Improvement
          Components: process
    Affects Versions: 3.0.0-incubating
            Reporter: Marko A. Rodriguez
            Assignee: Marko A. Rodriguez


I don't like the terms {{mapKeys()}} and {{mapValues()}}. I think we should use "select" as
the term for all projections out of a tuple. For instance, we do:

{code}
select('a') // get the object referenced by 'a' out of the incoming map
select('a','b') // get the objects referenced by 'a' and 'b' out of the incoming map
{code}

{{select()}} can even be used in situations that people don't typically think to use it.
gremlin> g.V().has('name','Die Hard').groupCount().by('name')
==>[Die Hard:1]
gremlin> g.V().has('name','Die Hard').groupCount().by('name').select('Die Hard')
==>1
gremlin> g.V().hasLabel('movie').groupCount().by('name').select('Die Hard','Toy Story','Jurassic
Park')
==>[Die Hard:1, Toy Story:1, Jurassic Park:1]
{code}

However, this assumes the keys are strings as {{select()}} only takes string arguments.

I think for all "project scenarios" the term should be "select." Thus, instead of {{mapKeys()}}
and {{mapValues()}}, we have:

{code}
select(keys) : Map -> Set<String>
select(values) : Map -> Collection<Object>
{code}

Moreover, I don't think these should be flatMap steps like {{mapXXX()}} as you are projecting
for EACH map (similar to how {{select('a','b')}} is not a flat map of a/b entires but maps
of a/b entries).

This type of select is different than the others as you are not projecting out a value for
an entry (row + key -> value), but a Collection value for column (map + key/value ->
collection). Regardless, it is still a projection of the incoming map (or path!). 



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