mingo/esm/operators/accumulator/percentile.js

MongoDB query language for in-memory objects

import {
  assert,
  findInsertIndex,
  has,
  isArray,
  isNumber,
  isObject
} from "../../util";
import { errInvalidArgs } from "../expression/_internal";
import { $push } from "./push";
const $percentile = (coll, expr, options) => {
  assert(
    isObject(expr) && has(expr, "input", "p") && isArray(expr.p),
    "$percentile expects object { input, p }"
  );
  const X = $push(coll, expr.input, options).filter(isNumber).sort();
  const centiles = $push(expr.p, "$$CURRENT", options);
  const method = expr.method || "approximate";
  const output = new Array(centiles.length);
  for (let i = 0; i < centiles.length; i++) {
    const p = centiles[i];
    if (!isNumber(p) || p < 0 || p > 1) {
      return errInvalidArgs(
        options.failOnError,
        "$percentile 'p' must resolve to array of numbers between [0.0, 1.0]"
      );
    }
    const r = p * (X.length - 1) + 1;
    const ri = Math.floor(r);
    const result = r === ri ? X[r - 1] : X[ri - 1] + r % 1 * (X[ri] - X[ri - 1]);
    switch (method) {
      case "exact":
        output[i] = result;
        break;
      case "approximate": {
        const pos = findInsertIndex(X, result);
        output[i] = pos / X.length >= p ? X[Math.max(pos - 1, 0)] : X[pos];
        break;
      }
    }
  }
  return output;
};
export {
  $percentile
};