flatten

fun <T> Sequence<Sequence<T>>.flatten(): Sequence<T>(source)

Returns a sequence of all elements from all sequences in this sequence.

The operation is intermediate and stateless.

Since Kotlin

1.0

Samples

import kotlin.test.*

fun main() { 
   //sampleStart 
   val sequence: Sequence<Int> = generateSequence(1) { it + 1 }
val sequenceOfSequences: Sequence<Sequence<Int>> = sequence.map { number ->
    generateSequence { number }.take(number)
}

println(sequenceOfSequences.flatten().take(10).toList()) // [1, 2, 2, 3, 3, 3, 4, 4, 4, 4] 
   //sampleEnd
}
xxxxxxxxxx
 
val sequence: Sequence<Int> = generateSequence(1) { it + 1 }
val sequenceOfSequences: Sequence<Sequence<Int>> = sequence.map { number ->
    generateSequence { number }.take(number)
}
println(sequenceOfSequences.flatten().take(10).toList()) // [1, 2, 2, 3, 3, 3, 4, 4, 4, 4] 
Open in Playground →
Target: JVMRunning on v.2.1.20

@JvmName(name = "flattenSequenceOfIterable")

fun <T> Sequence<Iterable<T>>.flatten(): Sequence<T>(source)

Returns a sequence of all elements from all iterables in this sequence.

The operation is intermediate and stateless.

Since Kotlin

1.0

Samples

import kotlin.test.*

fun main() { 
   //sampleStart 
   val sequence: Sequence<String> = sequenceOf("123", "45")
val sequenceOfLists: Sequence<List<Char>> = sequence.map { it.toList() }

println(sequenceOfLists.flatten().toList()) // [1, 2, 3, 4, 5] 
   //sampleEnd
}
xxxxxxxxxx
 
val sequence: Sequence<String> = sequenceOf("123", "45")
val sequenceOfLists: Sequence<List<Char>> = sequence.map { it.toList() }
println(sequenceOfLists.flatten().toList()) // [1, 2, 3, 4, 5] 
Open in Playground →
Target: JVMRunning on v.2.1.20

Thanks for your feedback!

Was this page helpful?