effect-io-ai

Package: effect
Module: Array

Array.groupBy

Groups elements into a record by a key-returning function. Each key maps to a NonEmptyArray of elements that produced that key.

When to use

Use to build buckets of elements indexed by a computed string or symbol key.

Details

Unlike group and groupWith, elements do not need to be adjacent to be grouped together. The key function must return a string or symbol.

Example (Grouping by a property)

import { Array } from "effect"

const people = [
  { name: "Alice", group: "A" },
  { name: "Bob", group: "B" },
  { name: "Charlie", group: "A" }
]

const result = Array.groupBy(people, (person) => person.group)
console.log(result)
// { A: [{ name: "Alice", group: "A" }, { name: "Charlie", group: "A" }], B: [{ name: "Bob", group: "B" }] }

See

• group — group adjacent equal elements
• groupWith — group adjacent elements by custom equality

Signature

declare const groupBy: { <A, K extends string | symbol>(f: (a: A) => K): (self: Iterable<A>) => Record<Record.ReadonlyRecord.NonLiteralKey<K>, NonEmptyArray<A>>; <A, K extends string | symbol>(self: Iterable<A>, f: (a: A) => K): Record<Record.ReadonlyRecord.NonLiteralKey<K>, NonEmptyArray<A>>; }

Source

Since v2.0.0