Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/10839#discussion_r56881462
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/linalg/distributed/BlockMatrix.scala
---
@@ -263,13 +263,33 @@ class BlockMatrix @Since("1.3.0") (
new CoordinateMatrix(entryRDD, numRows(), numCols())
}
+
/** Converts to IndexedRowMatrix. The number of columns must be within
the integer range. */
@Since("1.3.0")
def toIndexedRowMatrix(): IndexedRowMatrix = {
require(numCols() < Int.MaxValue, "The number of columns must be
within the integer range. " +
s"numCols: ${numCols()}")
- // TODO: This implementation may be optimized
- toCoordinateMatrix().toIndexedRowMatrix()
+
+ val rows = blocks.flatMap { case ((blockRowIdx, blockColIdx), mat) =>
+ mat.rowIter.zipWithIndex.map {
+ case (vector, rowIdx) =>
+ blockRowIdx * rowsPerBlock + rowIdx -> (blockColIdx,
vector.toBreeze)
+ }
+ }.groupByKey().map { case (rowIdx, vectors) =>
+
+ val wholeVector = vectors.head match {
+ case (idx, v: BDV[_]) => BDV.zeros[Double](numCols().toInt)
+ case (idx, v: BSV[_]) => BSV.zeros[Double](numCols().toInt)
+ case _ => throw new SparkException(s"Cannot convert an empty
vector to an indexed row")
+ }
+
+ vectors.foreach { case (blockColIdx: Int, vec: BV[Double]) =>
+ val offset = colsPerBlock * blockColIdx
+ wholeVector(offset until offset + vec.size) := vec
--- End diff --
(minor) `vec.size` should be the same as `colsPerBlock`.
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