@vect/matrix-init/index.js

An array util tool

function draft(h, w) {
  const mx = Array(h);
  for (--h; h >= 0; h--) mx[h] = Array(w);
  return mx
}

function iso(h, w, v) {
  const mx = Array(h);
  for (let i = 0, j, row; i < h; i++)
    for (j = 0, mx[i] = row = Array(w); j < w; j++)
      row[j] = v;
  return mx
}

function init(h, w, fn) {
  const mx = Array(h);
  for (let i = 0, j, row; i < h; i++)
    for (j = 0, mx[i] = row = Array(w); j < w; j++)
      row[j] = fn(i, j);
  return mx
}

function product(side, head, xyTo) {
  const h = side.length, w = head.length, mx = Array(h);
  for (let i = 0, j, row; i < h; i++) {
    for (j = 0, mx[i] = row = Array(w); j < w; j++) {
      row[j] = xyTo(side[i], head[j], i, j);
    }
  }
  return mx
}

function reshape(vec, h, w) {
  const mx = Array(h);
  for (let i = 0, b = 0; i < h; i++) {
    const row = mx[i] = Array(w);
    for (let j = 0; j < w; j++) row[j] = vec[b + j];
    b += w;
  }
  return mx
}

/** @deprecated */
function starter(h = 1, w = 1, { value, fn }) {
  if (value !== undefined && value !== null) return iso(h, w, value)
  if (fn) return init(h, w, fn)
  return draft(h, w)
}

const shallow = (mx) => mx.map(r => r.slice());

export { draft, init, iso, product, reshape, shallow, starter };