Fill missing data in a linear model-CodePudding

I have the following val list = listOf(1, 2, 3, null, null, 6, 7) I'd like to fill the null value for the following result: listOf(1, 2, 3, 4, 5, 6, 7)

I couldn't find any method doing this in Kotlin, do you guys have an idea?

EDIT: I'm adding more details, the list will always have a beginning element and an ending element (ie no list as listOf(null, 2 ,3) or listOf(1, 2, null)) I preprocess this.

In my example I gave Integer element but it could be Float or Double

CodePudding user response：

It's no idea to decide what number you what to replace with null.

Considing what if listOf(1, null, null) or listOf(null, 2, null).

If you know exactly what a list needs to be, you mignt use IntProgression or IntRange instead.

// 1, 2, 3, 4, 5, 6, 7
val list1 = IntRange(1, 7).toList()

// 1, 3, 5, 7
val list1 = IntProgression(1, 7, 2).toList()

CodePudding user response：

Try this

inline fun <T>List<T?>.replaceIfNull(block:(T) -> T) : List<T>{
    val temp = mutableListOf<T>()
    for((index, element) in this.withIndex()){
        if(element == null){
            temp.add(block(this[index - 1] ?: temp[index - 1]))
        } else {
            temp.add(element)
        }
    }
    return temp
}


fun main() {
   val list = listOf(1, 2, 3, null, null, 6, 7) 
   val foo = list.replaceIfNull { nonNullValue ->
       nonNullValue   1
   }
   println(foo) // [1, 2, 3, 4, 5, 6, 7]
}

test: https://pl.kotl.in/65yVIXkrj