Scala Array - index issue

Question

I have the below Array with me.

scala> var a1 =Array(1.1,2.4,3.6)
a1: Array[Double] = Array(1.1, 2.4, 3.6)

I need to get the index from this array based on the input value as below.Basically, I need two index for a three element array.

For ex- all the input between 1.1 and 2.4 should be in first bucket. and all the input between 2.5 and 3.6 should be in second bucket.

> 1.1 -> 0
> 1.5 -> 0
> 2.4 -> 1
> 3.5 -> 1
> 3.6 -> 1

I was trying this using a1.indexWhere(x <= _). But this will result in the last item ie, 3.6 will fall in 3rd index.

Is there any simple way to achieve this ?

I do not understand the logic of the expected output. Can you clarify how that index is computed? — Luis Miguel Mejía Suárez
– Luis Miguel Mejía Suárez, Commented May 21, 2020 at 13:05
If I understand correctly given x you want the index of the value that is <= x? What happens if x is < the first element in the array or larger than the last element? — Terry Dactyl
– Terry Dactyl, Commented May 21, 2020 at 13:25
For ex- all the input between 1.1 and 2.4 should be in first bucket. and all the input between 2.5 and 3.6 should be in second bucket. — abc_spark
– abc_spark, Commented May 21, 2020 at 13:30
@Terry then it should fall in first and last bucket respectively. Thats what I am trying to get here. — abc_spark
– abc_spark, Commented May 21, 2020 at 13:32

Alfilercio · Accepted Answer · 2020-05-21 13:36:05Z

1

Scala doesn't have a function for that behavior exclusively. Try this simple solution:

val tempIndex = a1.indexWhere(x <= _)
if (tempIndex == a1.length - 1) tempIndex - 1 else tempIndex

Test it here

answered May 21, 2020 at 13:36

Alfilercio

1,1186 silver badges13 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Terry Dactyl · Accepted Answer · 2020-05-21 13:51:16Z

1

Try something like this. For anything not in a bucket you will get -1.

a1.zip(a.tail).indexWhere{ case (min, max) => x > min && x <= max}

answered May 21, 2020 at 13:37

Terry Dactyl

1,86814 silver badges24 bronze badges