CODEWITHSUNDEEP
lambdakotlin
rost
rost

Reputation: 4075

Is there a way to zip part of the values in list using zipWithNext kotlin?

In the official documentation of the Kotlin language there is a function zipWithNextthat is presented as follows.

val letters = listOf("a", "b", "c", "d", "e", "f")
val pairs = letters.zipWithNext {a, b -> a + b} // [ab, bc, cd, de, ef]

Is there a way to summarize only part of the elements of this list, and leave the rest unchanged? For comparison, you can use another listOf("bc", "de"). In this case the final output should looks like [a, bc, de, f]

Upvotes: 1

Views: 2425

Answers (1)

forpas
forpas

Reputation: 164139

I assume that the initial list's size is an even number, otherwise you cannot get your expected result.

For 

val letters = listOf("a", "b", "c", "d", "e", "f")

with zipWithNext():

val pairs = (listOf("") + letters + listOf(""))
        .zipWithNext()
        .filterIndexed { index, _ -> index % 2 == 0 }
        .map { it.first + it.second }

with chunked(2):

val pairs = listOf(letters.first()) + 
            letters.subList(1, letters.size - 1).chunked(2).map { it[0] + it[1] } + 
            listOf(letters.last())

both give this result:

[a, bc, de, f]

Edit
As for the comparison list:

fun getNewList(list: List<String>, comparison: List<String>) : List<String> {
    val newList = mutableListOf<String>()
    var flag = false
    list.forEachIndexed { i, s ->
        if (i < list.size - 1) {
            if (!flag) {
                val item = s + list[i + 1]
                if (comparison.contains(item)) {
                    newList.add(item)
                    flag = true
                } else {
                    newList.add(s)
                }
            } else {
                flag = false
            }
        } else {
            newList.add(s)
        }
    }
    return newList
}

this code:

val letters = listOf("a", "b", "c", "d", "e", "f")
val comparison = listOf("bc", "de")
val newList = getNewList(letters, comparison)
println(newList)

will print:

[a, bc, de, f]

Upvotes: 2

Related Questions