Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/4109#discussion_r23589789
--- Diff: mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala
---
@@ -281,31 +344,53 @@ class SparseMatrix(
require(values.length == rowIndices.length, "The number of row indices
and values don't match! " +
s"values.length: ${values.length}, rowIndices.length:
${rowIndices.length}")
- require(colPtrs.length == numCols + 1, "The length of the column indices
should be the " +
- s"number of columns + 1. Currently, colPointers.length:
${colPtrs.length}, " +
- s"numCols: $numCols")
+ // The Or statement is for the case when the matrix is transposed
+ require(colPtrs.length == numCols + 1 || colPtrs.length == numRows + 1,
"The length of the " +
+ "column indices should be the number of columns + 1. Currently,
colPointers.length: " +
+ s"${colPtrs.length}, numCols: $numCols")
require(values.length == colPtrs.last, "The last value of colPtrs must
equal the number of " +
s"elements. values.length: ${values.length}, colPtrs.last:
${colPtrs.last}")
override def toArray: Array[Double] = {
val arr = new Array[Double](numRows * numCols)
- var j = 0
- while (j < numCols) {
- var i = colPtrs(j)
- val indEnd = colPtrs(j + 1)
- val offset = j * numRows
- while (i < indEnd) {
- val rowIndex = rowIndices(i)
- arr(offset + rowIndex) = values(i)
+ // if statement inside the loop would be expensive
+ if (!isTransposed) {
+ var j = 0
--- End diff --
Use `foreachActive`.
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