Github user johnc1231 commented on a diff in the pull request:
https://github.com/apache/spark/pull/17459#discussion_r117620801
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/linalg/distributed/IndexedRowMatrix.scala
---
@@ -108,8 +108,64 @@ class IndexedRowMatrix @Since("1.0.0") (
*/
@Since("1.3.0")
def toBlockMatrix(rowsPerBlock: Int, colsPerBlock: Int): BlockMatrix = {
- // TODO: This implementation may be optimized
- toCoordinateMatrix().toBlockMatrix(rowsPerBlock, colsPerBlock)
+ require(rowsPerBlock > 0,
+ s"rowsPerBlock needs to be greater than 0. rowsPerBlock:
$rowsPerBlock")
+ require(colsPerBlock > 0,
+ s"colsPerBlock needs to be greater than 0. colsPerBlock:
$colsPerBlock")
+
+ val m = numRows()
+ val n = numCols()
+ val lastRowBlockIndex = m / rowsPerBlock
+ val lastColBlockIndex = n / colsPerBlock
+ val lastRowBlockSize = (m % rowsPerBlock).toInt
+ val lastColBlockSize = (n % colsPerBlock).toInt
+ val numRowBlocks = math.ceil(m.toDouble / rowsPerBlock).toInt
+ val numColBlocks = math.ceil(n.toDouble / colsPerBlock).toInt
+
+ val blocks = rows.flatMap { ir: IndexedRow =>
+ val blockRow = ir.index / rowsPerBlock
+ val rowInBlock = ir.index % rowsPerBlock
+
+ ir.vector match {
+ case SparseVector(size, indices, values) =>
+ indices.zip(values).map { case (index, value) =>
+ val blockColumn = index / colsPerBlock
--- End diff --
So it is true that IndexedRowMatrix could have a Long number of rows, but
BlockMatrix is backed by an RDD of ((Int, Int), Matrix), so we're limited by
that. I can just add a check that computes whether it's possible to make a
BlockMatrix from the given IndexedRowMatrix.
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