mllib.Matrices.fromBreeze may crash when converting from Breeze sparse matrix

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Details

• Bug
• Status: Resolved
• Minor
• Resolution: Fixed
• 2.1.1
• None
• Patch

Description

Conversion of Breeze sparse matrices to Matrix is broken when matrices are product of certain operations. This problem I think is caused by the update method in Breeze CSCMatrix when they add provisional zeros to the data for efficiency.

This bug is serious and may affect at least BlockMatrix addition and substraction

The following code, reproduces the bug (Check test("breeze conversion bug"))

https://github.com/ghoto/spark/blob/test-bug/CSCMatrixBreeze/mllib/src/test/scala/org/apache/spark/mllib/linalg/MatricesSuite.scala

MatricesSuite.scala
```  test("breeze conversion bug") {
// (2, 0, 0)
// (2, 0, 0)
val mat1Brz = Matrices.sparse(2, 3, Array(0, 2, 2, 2), Array(0, 1), Array(2, 2)).asBreeze
// (2, 1E-15, 1E-15)
// (2, 1E-15, 1E-15
val mat2Brz = Matrices.sparse(2, 3, Array(0, 2, 4, 6), Array(0, 0, 0, 1, 1, 1), Array(2, 1E-15, 1E-15, 2, 1E-15, 1E-15)).asBreeze
// The following shouldn't break
val t01 = mat1Brz - mat1Brz
val t02 = mat2Brz - mat2Brz
val t02Brz = Matrices.fromBreeze(t02)
val t01Brz = Matrices.fromBreeze(t01)

val t1Brz = mat1Brz - mat2Brz
val t2Brz = mat2Brz - mat1Brz
// The following ones should break
val t1 = Matrices.fromBreeze(t1Brz)
val t2 = Matrices.fromBreeze(t2Brz)

}

```

People

Ignacio Bermudez Corrales
Ignacio Bermudez Corrales