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https://issues.apache.org/jira/browse/MAHOUT-1895?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15770360#comment-15770360
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ASF GitHub Bot commented on MAHOUT-1895:
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Github user rawkintrevo commented on the issue:
https://github.com/apache/mahout/pull/262
Thanks for the comments @dlyubimov . Do you mean we should add a method to
expose
[this](https://github.com/apache/mahout/blob/master/math/src/main/java/org/apache/mahout/math/DenseVector.java#L29)
for dense implementations?
For `SequentialAccessSparseVector` could we [expose the
`OrderedIntDoubleMapping`](https://github.com/apache/mahout/blob/master/math/src/main/java/org/apache/mahout/math/SequentialAccessSparseVector.java#L45)
underlying and then add a method [to expose `indices` and
`values`](https://github.com/apache/mahout/blob/master/math/src/main/java/org/apache/mahout/math/OrderedIntDoubleMapping.java#L26)
then zip them into a Map as a convenience.
Similarly for [`Int2DoubleOpenHashMap` backing `RandomAccessSparseVector`]
we could [expose
`values`](https://github.com/apache/mahout/blob/master/math/src/main/java/org/apache/mahout/math/RandomAccessSparseVector.java#L36)
and then using the interface for
`it.unimi.dsi.fastutil.ints.Int2DoubleOpenHashMap` we could [get the
`keySet()`](http://fastutil.di.unimi.it/docs/it/unimi/dsi/fastutil/ints/Int2DoubleOpenHashMap.html#keySet--)
and `values` which in turn are
[`IntSet`](http://fastutil.di.unimi.it/docs/it/unimi/dsi/fastutil/ints/IntSet.html)
and
[`DoubleCollection`](http://fastutil.di.unimi.it/docs/it/unimi/dsi/fastutil/doubles/DoubleCollection.html)
respectively, however both have `toArray()` methods.
If these are unacceptable, do you have any alternative approaches (and
apologies if I entirely missed your point regarding the `DenseVector`s)
> Add convenience methods for converting Vectors to Scala types
> -------------------------------------------------------------
>
> Key: MAHOUT-1895
> URL: https://issues.apache.org/jira/browse/MAHOUT-1895
> Project: Mahout
> Issue Type: Bug
> Affects Versions: 0.12.2
> Reporter: Trevor Grant
> Assignee: Trevor Grant
> Priority: Minor
> Fix For: 0.13.0
>
>
> While dense and sparse vectors may be created from `TraversableOnce[Double]`
> such as `Array[Double]` and `TraversableOnce[(Int, AnyVal)]` such as
> `Map[Int,Double]` respectively. Converting back into this format is somewhat
> tedious. We should add convenience methods to take care of this.
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