Matrix

MutableList<Vector>

Vector

MutableList<Double>

val A = Matrix(5, 5) { i, j -> 1 }
A.row(2) *= 3
A[0] += Vector(0.0, 1.0, 3.0, 4.0, 5.0)
println(A[2]) // < 3.0, 3.0, 3.0, 3.0, 3.0 >

fun row(i: Int) = this[i]
fun col(j: Int) = Vector(numRows) { this[it][j] }

Vector

Matrix

DoubleArray

(Mutable)MatrixSlice

subSlice

MutableList

Matrix

List

open class Matrix(data: List<List<Double>> = listOf()) : MutableList<Vector> by data.map({ it.toVector() }).toMutableList()

List

.map{}.toMutableList{}

mapTo

get(r,c) = arr[r*width + c]

set(r,c,v)

interface Vector {
    val size: Int
    operator fun get(i: Int): Double
}

fun Vector(elements: DoubleArray): Vector = BasicVector(elements)

private class BasicVector(val arr: DoubleArray): Vector {
    override val size: Int get() = arr.size
    override fun get(i: Int) = arr[i]
}

class Matrix(val width: Int, val height: Int) {
    private val arr = DoubleArray(width * height)

    private fun index(row: Int, col: Int) = row * width + col

    operator fun get(row: Int, col: Int) = arr[index(row, col)]
    operator fun set(row: Int, col: Int, value: Double) { arr[index(row, col)] = value }

    operator fun get(row: Int) = row(row)
    fun row(row: Int): Vector = RowVector(row)
    fun col(col: Int): Vector = ColVector(col)

    private inner class RowVector(val row: Int): Vector {
        override val size: Int get() = this@Matrix.width
        override fun get(i: Int) = this@Matrix[row, i]
    }

    private inner class ColVector(val col: Int): Vector {
        override val size: Int get() = this@Matrix.height
        override fun get(i: Int) = this@Matrix[i, col]
    }
}

Matrix

class DataFrame {
    val matrix: Matrix = ...
    val fileName: String = ...
    ...
}

+

-

mutableList

List

r * width + c

ArrayList

HashMap

DoubleArray

constructor() { val thisOne: Foo }

companion object {
    operator fun invoke(rows: List<List<Double>>): Matrix {
        val width = rows[0].size
        if (!rows.drop(1).all { it.size == width })
            throw IllegalArgumentException("All rows must be of equal length.")
        return Matrix(width, rows.flatten().toDoubleArray())
    }
}