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https://issues.apache.org/jira/browse/TINKERPOP-1237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15216468#comment-15216468
]
ASF GitHub Bot commented on TINKERPOP-1237:
-------------------------------------------
GitHub user okram opened a pull request:
https://github.com/apache/incubator-tinkerpop/pull/284
TINKERPOP-1237: ProjectMap: For the Love of Die Faterland
https://issues.apache.org/jira/browse/TINKERPOP-1237
Added `GraphTraversal.project()` which allows is like the inverse of
`select()`. Instead of pulling from this path history, you are pushing into the
future. While this can be done with `match()`, `ProjectStep` does not require
`LABELED_PATHS` and thus, is more efficient (though, its constrained to local
children `by()`-modulation).
EXAMPLE:
```
gremlin> g.V().out("created").
project("a","b").
by("name").
by(in("created").count()).
order().by(select("b"),decr).
select("a")
==>lop
==>lop
==>lop
==>ripple
```
CHANGELOG
```
* Added `GraphTraversal.project()` to allow projecting out a
`Map<String,E>` given the current traverser and an arbitrary number of
`by()`-modulators.
```
Docs build, `mvn clean install` and Giraph (at `ProjectTest`) tested.
VOTE +1.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/incubator-tinkerpop TINKERPOP-1237
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-tinkerpop/pull/284.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #284
----
commit d90be26f1625e376e93ce91adcff725de836a8e5
Author: Marko A. Rodriguez <[email protected]>
Date: 2016-03-29T17:44:52Z
Added ProjectStep and GraphTraversal.project() which is like select(), but
on the current traverser, not history data. As such, it does not require
path-computations, though its by()-modulators are local children. Added test
cases and updated docs.
----
> ProjectMap: For the Love of Die Faterland
> -----------------------------------------
>
> Key: TINKERPOP-1237
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1237
> Project: TinkerPop
> Issue Type: Improvement
> Components: process
> Affects Versions: 3.1.1-incubating
> Reporter: Marko A. Rodriguez
> Assignee: Daniel Kuppitz
>
> {code}
> gremlin> g.V(1).out("knows").
> project("a","b").by("name").by(outE().count())
> ==>{a:josh, b:2}
> ==>{a:vadas, b:0}
> {code}
> Its like {{select()}} by inverted -- thus, {{project()}}! Moreover, its a
> generalization of {{valueMap()}} and {{propertyMap}}.
> {code}
> public class ProjectStep<S,E> extends MapStep<S,Map<String,E>> {
> TraversalRing<S,E> ...
> String... keys;
> public Map<String,E> map(final Traverser.Admin<S> traverser) {
> final Map<String,E> result = new HashMap<>(keys.length);
> for(final String key : keys) {
> result.put(key, TraversalUtil.apply(traverser, traversalRing.next());
> }
> traversalRing.reset();
> return result;
> }
> }
> {code}
> cc/ Mein Obergruppenführer [~mbroecheler].
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