Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/17459#discussion_r118817991
--- Diff:
mllib/src/main/scala/org/apache/spark/mllib/linalg/distributed/IndexedRowMatrix.scala
---
@@ -108,8 +108,69 @@ 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")
+
+ // Since block matrices require an integer row index
+ require(numRows() / rowsPerBlock.toDouble <= Int.MaxValue,
--- End diff --
So I guess the previous `toBlockMatrix` would have failed too when the
number of rows exceeded this threshold? it looks like it, given how
CoordinateMatrix.toBlockMatrix works. Hm, I wonder if you should even put this
warning over there too because it will fail mysteriously otherwise. The result
might even be wrong.
BTW on second look, I realize this check isn't quite the same as the math
that's performed below: `math.ceil(m.toDouble / rowsPerBlock).toInt`. I think
you want to check exactly the same thing. Maybe move the check below the
declaration of m, n, and just say: `require(math.ceil(m.toDouble /
rowsPerBlock) <= Int.MaxValue)` That's very clear.
Also, cols need to be checked.
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