Scala Tutorial - Learn How To Use Partition Function With Examples

Steps

1. How to initialize a sequence which contains donut names and prices

The code below shows how to declare a Sequence of both type String and Double to represent donut names and prices in a single collection..

println("Step 1: How to initialize a sequence which contains donut names and prices")
val donutNamesAndPrices: Seq[Any] = Seq("Plain Donut", 1.5, "Strawberry Donut", 2.0, "Glazed Donut", 2.5)
println(s"Elements of donutNamesAndPrices = $donutNamesAndPrices")

You should see the following output when you run your Scala application in IntelliJ:

Step 1: How to initialize a sequence which contains donut names and prices
Elements of donutNamesAndPrices = List(Plain Donut, 1.5, Strawberry Donut, 2.0, Glazed Donut, 2.5)

2. How to split the sequence by the element types using partition function

The code below shows how to use the partition method to pattern match on elements of type String and Double in order to create two collections, that is, one for each type..

println("\nStep 2: How to split the sequence by the element types using partition function")
val namesAndPrices: (Seq[Any], Seq[Any]) = donutNamesAndPrices.partition {
  case name: String => true
  case price: Double => false
}
println(s"Elements of namesAndPrices = $namesAndPrices")

You should see the following output when you run your Scala application in IntelliJ:

Step 2: How to split the sequence by the element types using partition function
Elements of namesAndPrices = (List(Plain Donut, Strawberry Donut, Glazed Donut),List(1.5, 2.0, 2.5))

3. How to access the donut String sequence from Step 2

A tuple was created as a result of using the partition method in Step 2. The code below shows how to access the String elements which represent donut names.

println("\nStep 3: How to access the donut String sequence from Step 2")
println(s"Donut names = ${namesAndPrices._1}")

You should see the following output when you run your Scala application in IntelliJ:

Step 3: How to access the donut String sequence from Step 2
Donut names = List(Plain Donut, Strawberry Donut, Glazed Donut)

4. How to access the donut prices sequence from Step 2

In Step 3, we showed how to access the donut names. The code below shows how to access the donut prices collection.

println("\nStep 4: How to access the donut prices sequence from Step 2")
println(s"Donut prices = ${namesAndPrices._2}")

You should see the following output when you run your Scala application in IntelliJ:

Step 4: How to access the donut prices sequence from Step 2
Donut prices = List(1.5, 2.0, 2.5)

5. How to extract the pair returned by partition function

Similar to Step 2, we will once more call the partition method in order to split the original sequence from Step 1. However, in the example below, we will make use of an extractor to assign the tuple from the partition method into two sequences namely donutNames and donutPrices.

println("\nStep 5: How to extract the pair returned by partition function")
val (donutNames, donutPrices) = donutNamesAndPrices.partition {
  case name: String => true
  case _ => false
}
println(s"donutNames = $donutNames")
println(s"donutPrices = $donutPrices")

You should see the following output when you run your Scala application in IntelliJ:

Step 5: How to extract the pair returned by partition function
donutNames = List(Plain Donut, Strawberry Donut, Glazed Donut)
donutPrices = List(1.5, 2.0, 2.5)