groupBy
inline fun <K> ShortArray.groupBy(
keySelector: (Short) -> K
): Map<K, List<Short>>inline fun <K> FloatArray.groupBy(
keySelector: (Float) -> K
): Map<K, List<Float>>inline fun <K> DoubleArray.groupBy(
keySelector: (Double) -> K
): Map<K, List<Double>>inline fun <K> BooleanArray.groupBy(
keySelector: (Boolean) -> K
): Map<K, List<Boolean>>@ExperimentalUnsignedTypes inline fun <K> ULongArray.groupBy(
keySelector: (ULong) -> K
): Map<K, List<ULong>>@ExperimentalUnsignedTypes inline fun <K> UByteArray.groupBy(
keySelector: (UByte) -> K
): Map<K, List<UByte>>@ExperimentalUnsignedTypes inline fun <K> UShortArray.groupBy(
keySelector: (UShort) -> K
): Map<K, List<UShort>>Groups elements of the original array by the key returned by the given keySelector function applied to each element and returns a map where each group key is associated with a list of corresponding elements.
The returned map preserves the entry iteration order of the keys produced from the original array.
import kotlin.test.*
fun main(args: Array<String>) {
//sampleStart
val words = listOf("a", "abc", "ab", "def", "abcd")
val byLength = words.groupBy { it.length }
println(byLength.keys) // [1, 3, 2, 4]
println(byLength.values) // [[a], [abc, def], [ab], [abcd]]
val mutableByLength: MutableMap<Int, MutableList<String>> = words.groupByTo(mutableMapOf()) { it.length }
// same content as in byLength map, but the map is mutable
println("mutableByLength == byLength is ${mutableByLength == byLength}") // true
//sampleEnd
}inline fun <K, V> ShortArray.groupBy(
keySelector: (Short) -> K,
valueTransform: (Short) -> V
): Map<K, List<V>>inline fun <K, V> FloatArray.groupBy(
keySelector: (Float) -> K,
valueTransform: (Float) -> V
): Map<K, List<V>>inline fun <K, V> DoubleArray.groupBy(
keySelector: (Double) -> K,
valueTransform: (Double) -> V
): Map<K, List<V>>inline fun <K, V> BooleanArray.groupBy(
keySelector: (Boolean) -> K,
valueTransform: (Boolean) -> V
): Map<K, List<V>>@ExperimentalUnsignedTypes inline fun <K, V> ULongArray.groupBy(
keySelector: (ULong) -> K,
valueTransform: (ULong) -> V
): Map<K, List<V>>@ExperimentalUnsignedTypes inline fun <K, V> UByteArray.groupBy(
keySelector: (UByte) -> K,
valueTransform: (UByte) -> V
): Map<K, List<V>>@ExperimentalUnsignedTypes inline fun <K, V> UShortArray.groupBy(
keySelector: (UShort) -> K,
valueTransform: (UShort) -> V
): Map<K, List<V>>Groups values returned by the valueTransform function applied to each element of the original array by the key returned by the given keySelector function applied to the element and returns a map where each group key is associated with a list of corresponding values.
The returned map preserves the entry iteration order of the keys produced from the original array.
import kotlin.test.*
fun main(args: Array<String>) {
//sampleStart
val nameToTeam = listOf("Alice" to "Marketing", "Bob" to "Sales", "Carol" to "Marketing")
val namesByTeam = nameToTeam.groupBy({ it.second }, { it.first })
println(namesByTeam) // {Marketing=[Alice, Carol], Sales=[Bob]}
val mutableNamesByTeam = nameToTeam.groupByTo(HashMap(), { it.second }, { it.first })
// same content as in namesByTeam map, but the map is mutable
println("mutableNamesByTeam == namesByTeam is ${mutableNamesByTeam == namesByTeam}") // true
//sampleEnd
}Groups elements of the original collection by the key returned by the given keySelector function applied to each element and returns a map where each group key is associated with a list of corresponding elements.
The returned map preserves the entry iteration order of the keys produced from the original collection.
import kotlin.test.*
fun main(args: Array<String>) {
//sampleStart
val words = listOf("a", "abc", "ab", "def", "abcd")
val byLength = words.groupBy { it.length }
println(byLength.keys) // [1, 3, 2, 4]
println(byLength.values) // [[a], [abc, def], [ab], [abcd]]
val mutableByLength: MutableMap<Int, MutableList<String>> = words.groupByTo(mutableMapOf()) { it.length }
// same content as in byLength map, but the map is mutable
println("mutableByLength == byLength is ${mutableByLength == byLength}") // true
//sampleEnd
}Groups values returned by the valueTransform function applied to each element of the original collection by the key returned by the given keySelector function applied to the element and returns a map where each group key is associated with a list of corresponding values.
The returned map preserves the entry iteration order of the keys produced from the original collection.
import kotlin.test.*
fun main(args: Array<String>) {
//sampleStart
val nameToTeam = listOf("Alice" to "Marketing", "Bob" to "Sales", "Carol" to "Marketing")
val namesByTeam = nameToTeam.groupBy({ it.second }, { it.first })
println(namesByTeam) // {Marketing=[Alice, Carol], Sales=[Bob]}
val mutableNamesByTeam = nameToTeam.groupByTo(HashMap(), { it.second }, { it.first })
// same content as in namesByTeam map, but the map is mutable
println("mutableNamesByTeam == namesByTeam is ${mutableNamesByTeam == namesByTeam}") // true
//sampleEnd
}