scala sparseVetor， SprseMatrix 实现

Posted 2020-10-05 江枫1

def rand(seed:Int):Double={
  val rand=new Random(seed)
  rand.nextDouble()
}



def rand2(size:Int,seed:Int):SparseVector={
  val rand=new Random(seed)
  val ret_indices=Array.range(0,size)
  val ret_values=Array.tabulate[Double](size)(i=>rand.nextDouble())  //从函数创建数组
  Vectors.sparse(size, ret_indices, ret_values).asInstanceOf[SparseVector]
}

调用：val w=rand2(4,3)  
返回，SparseVector有3个要素函数，size,indices,values. 
取某一部分就调用那3个函数。比如：w.size=4,w.indices=(1,2,3,4)

def rand3(numRows:Int,numCols:Int,seed:Int):SparseMatrix={
  val rand=new Random(seed)
  val ret_rowIndices=new ArrayBuffer[Int]()
  for (i <-0 to numCols-1) {
    ret_rowIndices ++= Array.range(0,numRows)
  }
  val ret_colPtrs=Array.range(0,numCols+1).map(x=>x * numRows)
  val ret_values=Array.tabulate[Double](numRows*numCols)(i=>rand.nextDouble())
  Matrices.sparse(numRows, numCols, ret_colPtrs.toArray,ret_rowIndices.toArray, ret_values.toArray).asInstanceOf[SparseMatrix]
}