GitHub user javelinjs opened a pull request:
https://github.com/apache/spark/pull/9159
[SPARK-10757] [MLlib] Java friendly constructor for distributed matrices
This patch allows java developers to construct BlockMatrix and RowMatrix
more naturally.
Take BlockMatrix as an example, the type of 'blocks' in current constructor
is RDD[((Int, Int), Matrix)], while more precisely it should be RDD[((Int,
Int), T<:Matrix)]. This could cause some problem. If we add a Java-friendly
constructor
```{scala}
def this(blocks: JavaRDD[((Integer, Integer), Matrix)],
rowsPerBlock: Int,
colsPerBlock: Int)
```
and then construct a BlockMatrix with RDD[(Int, Int), DenseMatrix], the
complier will complain a conflict, like:
```
method constructor BlockMatrix with alternatives:
(blocks: org.apache.spark.api.java.JavaRDD[((Integer, Integer),
org.apache.spark.mllib.linalg.Matrix)],rowsPerBlock: Int,colsPerBlock:
Int)org.apache.spark.mllib.linalg.distributed.BlockMatrix <and>
(blocks: org.apache.spark.rdd.RDD[((Int, Int),
org.apache.spark.mllib.linalg.Matrix)],rowsPerBlock: Int,colsPerBlock:
Int)org.apache.spark.mllib.linalg.distributed.BlockMatrix
cannot be applied to (org.apache.spark.rdd.RDD[((Int, Int),
org.apache.spark.mllib.linalg.DenseMatrix)], Int, Int)
```
On the other hand, BlockMatrix should hide the underlying implementation of
sub-matrix, no matter it is dense or sparse. Thus, a class level covariant for
Matrix is improper. That's why I add a companion object method to construct
BlockMatrix/RowMatrix
For IndexedRowMatrix/CoordinateMatrix, since the RDD parameters for them
are really simple and contain no type inheritance, I don't see necessity to add
additional Java friendly apis for those two. Or do we need them to let java
users construct IndexedRowMatrix/CoordinateMatrix in the same way as what they
do with BlockMatrix/RowMatrix?
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/javelinjs/spark-1
i10757-java-friendly-dist-matrices
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/9159.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 #9159
----
commit 9de727bde64513cc3b8c17acb5fddfcdb2e7537d
Author: Yizhi Liu <[email protected]>
Date: 2015-10-18T07:42:42Z
[SPARK-10757]Java friendly constructor for distributed matrices
commit 9b3a675569889f94be5cde28e1f1b899cef07d74
Author: Yizhi Liu <[email protected]>
Date: 2015-10-18T12:11:49Z
[SPARK-10757] [MLlib] Java friendly constructor for distributed matrices
commit 8dbd4c5e4418324f329e26403239337c70e04804
Author: Yizhi Liu <[email protected]>
Date: 2015-10-18T12:15:16Z
[SPARK-10757] [MLlib] Java friendly constructor for distributed matrices
----
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