scala实现Matrix矩阵类

快学Scala Chapter11 操作符练习解答

12.8 提供一个Matrix类—你可以选择需要的是一个2*2的矩阵，任意大小的正方形矩阵，或m*n的矩阵。支持+和*操作。*操作应同样适用于单值，例如mat*2。单个元素可以通过

mat(row,col)得到

import scala.collection.mutable.ArrayBuffer

/**

* @author LiRuiqi

*/

class Matrix(private val data:Array[Int],private val nrow:Int){

val cols = (data.length.toFloat/nrow).ceil.toInt

private val matrixData:Array[Array[Int]] = {

val result:Array[Array[Int]] = Array.ofDim[Int](nrow,cols)

for(i <- 0until nrow){

for(j <- 0until cols){

val index = i*cols+j

result(i)(j) = if(data.isDefinedAt(index)) data(index) else0

}

}

result

}

override def toString = {

var str = ""

matrixData.map((p:Array[Int]) => {p.mkString(",")}).mkString("\n") }

def*(a:Matrix) = {

if(this.cols!=a.nrow)

println("error!") else {

val data:ArrayBuffer[Int] = ArrayBuffer()

for(i <- 0to this.nrow-1){

for(j <- 0to a.cols-1){

var num = 0

for(b <- 0to this.cols-1){

num += this.matrixData(i)(b) *a.matrixData(b)(j)

}

data+=num

}

}

new Matrix(data.toArray,this.nrow)

}

}

def*(a:Int) = {

val data:ArrayBuffer[Int] = ArrayBuffer()

for(i <- 0to this.matrixData.length-1){

for(j <- 0to this.matrixData(0).length-1){

data+=this.matrixData(i)(j) *a

}

}

new Matrix(data.toArray,this.matrixData.length)

}

def+(a:Matrix) = {

if(this.nrow!=a.nrow||this.cols!=a.cols)

println("error!") else {

val data:ArrayBuffer[Int] = ArrayBuffer()

for(i <- 0to this.matrixData.length-1){

for(j <- 0to this.matrixData(0).length-1){

data+=this.matrixData(i)(j) +a.matrixData(i)(j) }

}

new Matrix(data.toArray,this.matrixData.length)

}

}

def mat(row:Int,col:Int) = {

matrixData(row-1)(col-1)

}

}

object Question8 {

def main(args: Array[String]): Unit = {

val m = new Matrix(Array(1,2,3,4),2)

val n = new Matrix(Array(1,3,5,8),2)

println( m+"\n")

println( n+"\n")

println( m*n+"\n")

println( m+n+"\n")

println( m.mat(2,2) +"\n")

println( m*10+"\n")

}

}