lo/docs/data/it-countvaluesby.md

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

name	slug	sourceRef	category	subCategory	signatures	variantHelpers	similarHelpers	position
CountValuesBy	countvaluesby	it/seq.go#L720	it	slice	func CountValuesBy[T any, U comparable](collection iter.Seq[T], transform func(item T) U) map[U]int		core#slice#countvaluesby	204

CountValuesBy counts the number of each element returned from transform function. Is equivalent to chaining Map and CountValues.

type Person struct {
    Name string
    Age  int
}

collection := func(yield func(Person) bool) {
    yield(Person{"Alice", 25})
    yield(Person{"Bob", 30})
    yield(Person{"Charlie", 25})
    yield(Person{"Diana", 30})
}

countsByAge := it.CountValuesBy(collection, func(p Person) int {
    return p.Age
})
// countsByAge contains {25: 2, 30: 2}