What is the easiest way to transpose 2 dimentional list in kotlin? ``` // now listOf( li...

# announcements

[igor.wojda]

What is the easiest way to transpose 2 dimentional list in kotlin?

// now
listOf(
            listOf(1, 2),
            listOf(3, 4)
        )

// want
listOf(
            listOf(3, 1),
            listOf(4, 2)
        )

[Robert Jaros]

My proposition 🙂

with(now.reversed()) {
    (0..1).map { i -> map { it[i] } }
}

[Robert Jaros]

Of course it works only for 2x2 😉

[Hamza]

typealias Vector = DoubleArray
typealias Matrix = Array<Vector>

fun Matrix.transpose(): Matrix {
val rows = this.size
val cols = this[0].size
val trans = Matrix(cols) { Vector(rows) }
for (i in 0 until cols) {
for (j in 0 until rows) trans[i][j] = this[j][i]
}
return trans
}