Taking Array values based on a condition

Question

I have the below arrays with me

 scala> arr1
res77: Array[Array[Int]] = Array(Array(5, 1, 99), Array(1, 2, 99), Array(2, 3, 99), Array(5, 6, 99))

scala> arr2
res78: Array[Array[Int]] = Array(Array(5, 1, 110), Array(1, 2, 110), Array(2, 3, 110), Array(5, 6, 110))

The third element of each item of this array will be a constant value(ie, 99 for first and 110 for second). I have to take the values from the array, based on this third element

ie, if the third element <=100 , I have to get those items in the array whose second element is < 5

if the third element >100 , I have to get those items in the array whose second element is > 5

Expected Output:

Array[Array[Int]] = Array(Array(5, 1, 99), Array(1, 2, 99), Array(2, 3, 99) ) //Output for arr1
Array[Array[Int]] = Array(Array(5, 6, 110)) //Output for arr2

How can i make a generalized code ?

Guru Stron · Accepted Answer · 2020-06-22 11:53:39Z

2

If you are guaranteed to have 3rd element to be the same you can try something like this:

arr1.filter(arr => {if (arr(2) <= 100) arr(1) < 5 else arr(1) > 5 })

answered Jun 22, 2020 at 11:53

Guru Stron

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Comments

Pedro Correia Luis · Accepted Answer · 2020-06-22 11:54:55Z

Not sure what you call a generalised code, but this is how I would do it:

First you can have n method equal to the number of conditions you desire.

def filterArrayByCondition1(input: Array[Array[Int]]): Array[Array[Int]] = {
    input.filter { arr =>
      val optConstant: Option[Int] = arr.lift(2)
      val optDecider: Option[Int] = arr.lift(1)

      val optCondition: Option[Boolean] = for {
        constant <- optConstant
        decider <- optDecider
      } yield {
        constant <= 100 && decider < 5
      }
      optCondition.getOrElse(false)

    }
  }

  def filterArrayByCondition2(input: Array[Array[Int]]): Array[Array[Int]] = {

    input.filter { arr =>
      val optConstant: Option[Int] = arr.lift(2)
      val optDecider: Option[Int] = arr.lift(1)

      val optCondition = for {
        constant <- optConstant
        decider <- optDecider
      } yield {
        constant > 100 && decider > 5
      }

      optCondition.getOrElse(false)

    }

  }

// you then can call them like this
filterArrayByCondition1(arr1).foreach(arr => println(arr.toSeq))
filterArrayByCondition2(arr2).foreach(arr => println(arr.toSeq))

Or define a condition like this:

val condition1: Array[Int] => Boolean = { arr: Array[Int] =>
    val optConstant: Option[Int] = arr.lift(2)
    val optDecider: Option[Int] = arr.lift(1)

    val optCondition: Option[Boolean] = for {
      constant <- optConstant
      decider <- optDecider
    } yield {
      constant <= 100 && decider < 5
    }

    optCondition.getOrElse(false)

  }

 // you then can call them like this
 arr1.filter(condition1.apply).foreach(arr => println(arr.toSeq))

Or combine them both to have maybe the cleanest:

def filterArrayByCondition(input: Array[Array[Int]], condition: Array[Int] => Boolean): Array[Array[Int]] = {
    input.filter(condition)
  }

// you then can call them like this
filterArrayByCondition(arr1, condition1).foreach(arr => println(arr.toSeq))

At the end you will have to define the condition that you want to filter the arrays, so the generalised code that you desire seems to be the last option that I gave you.

Hope it helped.

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