kotlin-stdlib/kotlin.text/flatMapIndexed

flatMapIndexed

@JvmName(name = "flatMapIndexedIterable")
inline fun <R> CharSequence.flatMapIndexed(transform: (index: Int, Char) -> Iterable<R>): List<R>(source)

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.

Since Kotlin

1.4

Samples

import kotlin.test.*

fun main() { 
   //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
}