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 <- 0 until nrow){
for(j <- 0 until cols){
val index = i*cols + j
result(i)(j) = if(data.isDefinedAt(index)) data(index) else 0
}
}
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 <- 0 to this.nrow -1){
for(j <- 0 to a.cols -1){
var num = 0
for(b <- 0 to 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 <- 0 to this.matrixData.length - 1){
for(j <- 0 to 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 <- 0 to this.matrixData.length - 1){
for(j <- 0 to 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")
}。