flatMapIndexed

Common
JVM
JS
Native
1.4
@JvmName("flatMapIndexedIterable") inline fun <R> CharSequence.flatMapIndexed(
    transform: (index: Int, Char) -> Iterable<R>
): List<R>

Returns a single list of all elements yielded from results of transform function being invoked on each character and its index in the original char sequence.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val data: List<String> = listOf("Abcd", "efgh", "Klmn")
val selected: List<Boolean> = data.map { it.any { c -> c.isUpperCase() } }
val result = data.flatMapIndexed { index, s -> if (selected[index]) s.toList() else emptyList() }
println(result) // [A, b, c, d, K, l, m, n]
//sampleEnd
}