CODEWITHSUNDEEP
scalascala-breeze
Ahsan Ijaz
Ahsan Ijaz

Reputation: 103

Breeze Vector to matrix conversion

Is there any way to convert breeze vector to breeze matrix of row/column size 1? I'm new in Scala and found it quite useful in past to write functions that handle vectors and matrices seamlessly (mostly in Matlab). For example, I would like func in following code to take as input either subsetMatrix or subsetVector.

val dummyMatrix = DenseMatrix.eye[Double](3)
val subsetMatrix = dummyMatrix(::,0 to 2)
val subsetVector = dummyMatrix(::,1)


def func(X1: DenseMatrix[Double]): Int = {
// Some operation on X1
}

Upvotes: 2

Views: 3332

Answers (2)

ely
ely

Reputation: 77424

A better solution is often to use range slicing when creating subsetVector in the first place (if you want it to be an Nx1 matrix-type instead of length-N vector type). For example:

val subsetSingleColumnMatrix = dummyMatrix(::, 0 until 1)

such as:

scala> val z = DenseMatrix.rand[Double](3, 3)
z: breeze.linalg.DenseMatrix[Double] =
0.9523399908830603    0.5140714248369589   0.23363266806760596
0.27656335841627455   0.2143774018347031   0.3116275714282011
0.020435608706944386  0.13954770594758292  0.5493312961226657

scala> z(::, 0 until 1)
res47: breeze.linalg.DenseMatrix[Double] =
0.9523399908830603
0.27656335841627455
0.020435608706944386

Upvotes: 1

dlwh
dlwh

Reputation: 2293

use asDenseMatrix

scala> import breeze.linalg._
import breeze.linalg._

scala> val dv = DenseVector(1, 2, 3)
dv: breeze.linalg.DenseVector[Int] = DenseVector(1, 2, 3)

scala> dv.asDenseMatrix
res0: breeze.linalg.DenseMatrix[Int] = 1  2  3

scala> (res0.rows, res0.cols)
res1: (Int, Int) = (1,3)

scala>

Upvotes: 5

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