Transposing Matrices with Scala's Arrays | CodeSignal Learn

Transposing Matrices with Scala's Arrays | CodeSignal Learn

Introduction

Welcome to another engaging exercise designed to refine your Scala programming skills! In this unit, we're diving into the fascinating world of matrices . Our main focus will be on transposing a given matrix. Let's embark on this matrix manipulation challenge using Scala's powerful capabilities!

Task Statement

Let's break down the task at hand. Your goal is to create a Scala function named transformMatrix . This function should accept a 2D array (which represents a matrix) containing integers as input. Your task is to return another 2D array, which is the transposed version of the provided matrix. Transposing a matrix involves switching its rows and columns. In simpler terms, every row of the original matrix should become a column in the transposed matrix, and vice versa. For instance, if the original matrix (input 2D array) is: Scala Array(Array(1, 2, 3), Array(4, 5, 6)) Then the transposed matrix (output 2D array) should be: Scala Array(Array(1, 4), Array(2, 5), Array(3, 6)) It's crucial to preserve the integrity of the data type present in the original matrix. In this case, the values in the input matrix are integers, so they should remain integers in the output matrix as well.

Solution Building: Step 1

The first step in constructing our solution is determining the dimensions of the matrix. We need to know the number of rows and columns it contains. In Scala, we can use the .length method to obtain this information. The number of rows corresponds to the length of the outer array, and the number of columns equals the length of any inner array (assuming it's not empty). Scala def transformMatrix(matrix: Array[Array[Int]]): Array[Array[Int]] = {val rows = matrix.length val cols = if (rows > 0) matrix(0).length else 0

Solution Building: Step 2

Next, we need to create a placeholder for the transposed matrix with appropriate dimensions. This will be a new 2D array where the number of rows and columns are swapped. Initially, we'll populate this matrix with zeros. Scala def transformMatrix(matrix: Array[Array[Int]]): Array[Array[Int]] = {val rows = matrix.length val cols = if (rows > 0) matrix(0).length else 0 val result = Array.fill(cols, rows)(0)

Sign up

Join the 1M+ learners on CodeSignal

Be a part of our community of 1M+ users who develop and demonstrate their skills on CodeSignal

Solution Building: Step 3

Now, let's get to the main task of transposing the matrix. For each element in the original matrix, we want to move it from the ith row and jth column to the jth row and ith column of the transposed matrix. A simple nested for-loop in Scala will efficiently accomplish this transformation for all elements of the matrix. def transformMatrix(matrix: Array[Array[Int]]): Array[Array[Int]] = { val rows = matrix.length val cols = if (rows > 0) matrix(0).length else 0 val result = Array.fill(cols, rows)(0) for (i <- 0 until rows) { for (j <- 0 until cols) { result(j)(i) = matrix(i)(j) } } result } // Example usage within the main function def main(args: Array[String]): Unit = { // Initial matrix (2D array) val matrix = Array( Array(1, 2, 3), Array(4, 5, 6) ) // Call our function on the matrix and output the result val transposed = transformMatrix(matrix) println(transposed.map(_.mkString(" ")).mkString("\n")) // Outputs: [[1, 4], [2, 5], [3, 6]] }

Alternative Solution

Another possible solution could utilize Scala's functional programming features to directly fill the new matrix: def transformMatrix(matrix: Array[Array[Int]]): Array[Array[Int]] = {val rows = matrix.length val cols = if (rows > 0) matrix(0).length else 0 Array.tabulate(cols, rows)((i, j) => matrix(j)(i))} Here, we fill the matrix directly at creation, where the value at the j th column of the i th row of the new matrix is assigned matrix(j)(i) .

Scala

def transformMatrix(matrix: Array[Array[Int]]): Array[Array[Int]] = {
  val rows = matrix.length
  val cols = if (rows > 0) matrix(0).length else 0
  val result = Array.fill(cols, rows)(0)

  for (i <- 0 until rows) {
    for (j <- 0 until cols) {
      result(j)(i) = matrix(i)(j)
    }
  }
  
  result
}

// Example usage within the main function
def main(args: Array[String]): Unit = {
  // Initial matrix (2D array)
  val matrix = Array(
    Array(1, 2, 3),
    Array(4, 5, 6)
  )

  // Call our function on the matrix and output the result
  val transposed = transformMatrix(matrix)
  println(transposed.map(_.mkString(" ")).mkString("\n")) // Outputs: [[1, 4], [2, 5], [3, 6]]
}

Scala

def transformMatrix(matrix: Array[Array[Int]]): Array[Array[Int]] = {
  val rows = matrix.length
  val cols = if (rows > 0) matrix(0).length else 0
  Array.tabulate(cols, rows)((i, j) => matrix(j)(i))
}