lo/docs/data/parallel-groupby.md

name, slug, sourceRef, category, subCategory, playUrl, similarHelpers, position, signatures, variantHelpers

name	slug	sourceRef	category	subCategory	playUrl	similarHelpers	position	signatures	variantHelpers
GroupBy	groupby	parallel/slice.go#L73	parallel	slice		core#slice#groupby core#slice#groupbymap parallel#slice#partitionby	30	func GroupBy[T any, U comparable, Slice ~[]T](collection Slice, iteratee func(item T) U) map[U]Slice	parallel#slice#groupby

Returns a map composed of keys generated from the results of running each element of the collection through the predicate. The predicate is called in parallel. Values keep the input order within each group.

import (
    lop "github.com/samber/lo/parallel"
)

groups := lop.GroupBy([]int{0, 1, 2, 3, 4, 5}, func(i int) int {
    return i % 3
})
// map[int][]int{0: {0, 3}, 1: {1, 4}, 2: {2, 5}}

Custom key types work as long as they are comparable:

type Kind string
groups2 := lop.GroupBy([]string{"go", "rust", "java"}, func(s string) Kind {
    if len(s) <= 2 { return "short" }
    return "long"
})
// map[Kind][]string{"short": {"go"}, "long": {"rust", "java"}}