Like _.mean, except each element is passed through an iteratee first — then those results are averaged. Part of Lodash 4.x Math (since 4.7.0).
Pass the numbers or collection shown below. Check the return value before you chain another math helper.
Call _.meanBy. Start with this line.
_.meanBy(array, [iteratee=_.identity])| Call | What it does |
|---|---|
_.meanBy(array, [iteratee=_.identity]) | Primary signature. |
_.meanBy(array, iteratee) | Run the math helper on numbers or a collection. |
Prefer import meanBy from "lodash/meanBy" when you want a smaller bundle.
_.meanBy(array, [iteratee=_.identity])| Parameter | Description |
|---|---|
| array | Required. Collection to iterate |
| iteratee | Optional. Function or property path; default identity |
| Return Value | Description |
|---|---|
| * | Mean of projected values, or NaN if empty |
Average n with an explicit callback.
var objects = [{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }];
_.meanBy(objects, function (o) {
return o.n;
});
// → 5n.[4, 2, 8, 6].20 / 4 = 5.(value).Same result with the "n" path.
var objects = [{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }];
_.meanBy(objects, "n");
// → 5"n" acts like o => o.n.4, 2, 8, 6."score.value" also work.Same empty rule as _.mean.
_.meanBy([], "n");
// → NaN
_.meanBy(null, "n");
// → NaN
Number.isFinite(_.meanBy([], "n"));
// → false0 / 0.NaN fallback.Number.isFinite before display.0 and not undefined.Undefined projections still inflate the divisor.
var rows = [{ n: 10 }, { n: 20 }, {}];
_.meanBy(rows, "n");
// → 10 // (10 + 20) / 3
_.meanBy([{ n: 10 }, { n: 20 }], "n");
// → 15{} projects to undefined.10 + 20 contribute.3 (full array length)._.mean and _.sumByPick average vs total, raw vs projected.
var objects = [{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }];
var nums = [4, 2, 8, 6];
_.meanBy(objects, "n");
// → 5
_.mean(nums);
// → 5
_.sumBy(objects, "n");
// → 20_.meanBy is a Lodash 4.x Math helper (since 4.7.0). It runs anywhere Lodash runs — modern browsers (CDN or bundle) and Node.js / Bun / Deno with npm install lodash. Native cousin: map + reduce / length.
Available in [email protected] full builds and the lodash/meanBy modular import. Works in evergreen browsers and current Node LTS when Lodash is installed.
Bottom line: Safe for production once Lodash is loaded. Prefer import meanBy from "lodash/meanBy" for smaller builds. Ideal for averaging object fields.
Find the smallest value in an array of numbers.
9 people found this page helpful