@thi.ng/tensors/filtered-indices.js

0D/1D/2D/3D/4D tensors with extensible polymorphic operations and customizable storage

import { defOpRT } from "./defoprt.js";
const filteredIndices = (pred) => defOpRT(
  (acc, data, i) => {
    if (pred(data[i])) acc.push(i);
    return acc;
  },
  () => []
);
const nonZeroIndices = filteredIndices((x) => x !== 0);
const negativeIndices = filteredIndices((x) => x < 0);
const positiveIndices = filteredIndices((x) => x > 0);
export {
  filteredIndices,
  negativeIndices,
  nonZeroIndices,
  positiveIndices
};