mingo
Version:
MongoDB query language for in-memory objects
22 lines (21 loc) • 715 B
JavaScript
import { isNumber } from "../../util";
import { $push } from "../accumulator";
import { MILLIS_PER_UNIT } from "./_internal";
function $derivative(_, collection, expr, options) {
if (collection.length < 2)
return null;
const { input, unit } = expr.inputExpr;
const sortKey = "$" + Object.keys(expr.parentExpr.sortBy)[0];
const values = [collection[0], collection[collection.length - 1]];
const points = $push(values, [sortKey, input], options).filter(
([x, y]) => isNumber(+x) && isNumber(+y)
);
if (points.length !== 2)
return null;
const [[x1, y1], [x2, y2]] = points;
const deltaX = (x2 - x1) / (MILLIS_PER_UNIT[unit] || 1);
return (y2 - y1) / deltaX;
}
export {
$derivative
};