有没有一种方便的方法可以在 Chapel 中用随机值填充稀疏数组？

Question

我正在比较使用和不使用语言环境的矩阵乘法，并且我正在尝试使用稀疏矩阵来处理线性代数模块。我计划使用 blockdist 并使用循环手动将其分解，但我希望能够看看我现在是否可以使用更简单的东西来获得加速。如果有一种简单的方法可以使用我忽略的 blockdist，我将不胜感激。无论如何，当我只用一个值填充稀疏数组时，我能够让代码工作并看到加速，但是用随机值填充它似乎不起作用：

use LayoutCS;
use Time;
use LinearAlgebra, Norm;
use LinearAlgebra.Sparse;
use Random;
use IO;

writeln("Please type the filename with your matrix dimensions. One matrix on each line. The rows in the second need to match the columns in the first");
var filename: string;
filename = stdin.read(string);

// Open an input file with the specified filename in read mode.
var infile = open(filename, iomode.r);
var reader = infile.reader();

// Read the number of rows and columns in the array in from the file.
var r = reader.read(int), c = reader.read(int);

const parentDom = {1..r, 1..c};
var csrDom: sparse subdomain(parentDom) dmapped CS();
var A: [csrDom] real; 
A = 2; //instead of this I would like to do something like fillRandom(A) but it seems to not work

var X: [1..r, 1..c] real; 
fillRandom(X);

//read in the other matrix
var r1 = reader.read(int), c1 = reader.read(int);

const parentDom1 = {1..r1, 1..c1};
var csrDom1: sparse subdomain(parentDom1) dmapped CS();
var B: [csrDom1] real;
B = 3; //same thing as with matrix A

var Y: [1..r1, 1..c1] real; 
fillRandom(Y);

// Close the file.
reader.close();
infile.close();

var t: Timer; //sets up timer
t.start();

var result: [1..r, 1..c1] real; //sets up matrix for results
  
forall i in 1..r do //goes through rows in 1st
  for j in 1..c1 do //goes through 2nd matrix columns
    for k in 1..c do { //goes through columns in 1st
      result[i, j] += X[i, k] * Y[k, j]; //adds the multiplications to the new slot in results
    }

t.stop();
writeln("multiplication took ", t.elapsed()," seconds");
t.clear();


t.start();
var res = A * B;
t.stop();

writeln("loc multiplication took ", t.elapsed()," seconds");
t.clear();

fillRandom 不适用于稀疏数组还是我做错了？我是否需要通过循环手动分配数组中的每个值？当然，我也有可能走错了路，应该更多地关注 blockdist在 blockdist 创建的正确语言环境部分上。

提前谢谢你！

Answer 1

fillRandom 不适用于稀疏数组还是我做错了？

Random.fillRandom() 在今天的 Chapel (1.22.0) 中不支持稀疏数组。但是，如果您有兴趣在其上提交 GitHub 问题，我认为这将是一个合理的功能请求。

即使fillRandom 支持稀疏数组，用户仍然需要在用随机值填充这些非零元素之前指定哪些元素是非零的。这是通过将索引作为(int, int) 元组（或(int, int) 元组的数组）添加到稀疏域来完成的。

下面是一个生成 100x100 压缩稀疏行 (CSR) 数组的小示例，其中包含 10 个非零随机元素：

/* Example tested with Chapel 1.22 */
import LayoutCS.{CS, isCSType};
import Random;

/* Parent domain dimensions: NxN */
config const N = 100;
/* Number of non-zero elements */
config const nnz = 10;

const parentDom = {1..N, 1..N};
var csrDom: sparse subdomain(parentDom) dmapped CS();
var A: [csrDom] real;

populate(A, csrDom, nnz);

// Print non-zero elements
for (i,j) in csrDom do
  writeln((i,j), ':', A[i, j]);


/* Populate sparse matrix with `nnz` random values */
proc populate(ref A, ref ADom, nnz: int) where isCSType(ADom.dist.type) && isCSType(A.domain.dist.type) {

  // Generate array of random non-zero indices
  var indices: [1..nnz] 2*int;
  var randomIndices = Random.createRandomStream(eltType=int);

  // Replace any duplicate indices with a new random index
  for idx in indices {
    var newIdx = idx;
    while indices.find(newIdx)(1) {
      newIdx = (randomIndices.getNext(ADom.dim(0).low, ADom.dim(0).high),
                randomIndices.getNext(ADom.dim(1).low, ADom.dim(1).high));
    }
    idx = newIdx;
  }

  // Add the non-zero indices to the CSR domain
  ADom += indices;

  // Generate random elements - maybe fillRandom(A) could do this for us some day
  var randomElements = Random.createRandomStream(eltType=A.eltType);
  for idx in ADom {
    A[idx] = randomElements.getNext();
  }
}