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Scala Trait Traversable | Set-2
  • Last Updated : 15 Apr, 2019

prerequisite- Scala Trait Traversable | Set-1

In the previous Set we have seen some of the operations performed by the Class Taversable. Now, in this Set we will perceive some more operations.
These operations are as follows:

  • Conversion operations:
    The Conversion operations are toList, toSeq, toArray, toStream, toSet, toMap, toIterable, and toIndexedSeq. These operations changes the Collection of Traversable into a relatively distinct thing.
    Example :




    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating Set of numbers 
            val q = Set(2, 7, 8, 15, 19)
      
            // Converting Set to an Array
            val r = q.toArray 
      
            // Displaying an Array
            println(r)
        }
    }
    Output:
    [I@506e1b77
    

    Here, the Conversion operation i.e, toArray will convert the above Set (or any Traversable) into an Array.
    Example :






    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating Set of numbers 
            val q = Set(2, 6, 3, 7, 15, 20)
      
            // Converting a Set to a List
            val r = q.toList
      
            // Displaying a List
            println(r)
              
        }
    }
    Output:
    List(20, 6, 2, 7, 3, 15)
    

    Here, toList will convert any Collection of Traversable into a List.
    Example :




    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating List of numbers 
            val x = List(9, 10, 13, 15, 18, 19)
      
            // Converting a List to a Set
            val y = x.toSet
      
            // Displaying a Set
            println(y)
        }
    }
    Output:
    Set(10, 9, 13, 18, 19, 15)
    

    Here, the Conversion operation i.e, toSet will convert any collection of Traversable into a Set.
    Example :




    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating Set of numbers 
            val m = Set(2, 4, 6, 8, 11, 15)
      
            // Converting a Set to a Sequence
            val n = m.toSeq
      
            // Displaying a Sequence
            println(n)
        }
    }
    Output:
    ArrayBuffer(6, 2, 11, 8, 4, 15)
    

    Here, Conversion operation i.e, toSeq converts any Collection of Traversable into a Sequence. The sequence generated here is utilized in Vectors.
    Example :




    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating Set of numbers 
            val x = Set(8, 10, 13, 15, 18)
      
            // Converting a Set to an Iterable
            val y = x.toIterable
      
            // Displaying an iterable
            println(y)
        }
    }
    Output:
    Set(10, 13, 18, 8, 15)
    

    Here, the Conversion operation i.e, toIterable (It Iterates over all the elements of the collection) will convert any collection of a Traversable into an Iterable.
    Example :






    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating Set of numbers 
            val x = Set(2, 4, 5, 6, 7, 9)
      
            // Convrerting a Set to an 
            // Indexed sequence 
            val y = x.toIndexedSeq
      
            // Displaying an Indexed sequence
            println(y)
        }
    }
    Output:
    Vector(5, 6, 9, 2, 7, 4)
    

    Here, the conversion operation i.e, toIndexedSeq converts any Traversable into an Indexed sequence. The Indexed sequence generated here is utilized in Strings and Vectors.
    Example :




    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating Set of numbers 
            val x = Set(15, 17, 18, 19, 22, 25)
      
            // Converting a Set to a stream 
            val y = x.toStream
      
            // Displaying a Stream
            println(y)
        }
    }
    Output:
    Stream(25, ?)
    

    Here, the Conversion operation i.e, toStream converts any collection of Traversable into a Stream. This Stream is enumerated lazily.
    Example :




    // Scala program of Conversion operation
      
    // Creating object 
    object Conversion
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a Set of parameters 
            val x = Set("GfG" -> "CS portal", "Nidhi" -> "a Geek")
      
            // Converting a Set to a Map
            val y = x.toMap
      
            // Displaying a Map
            println(y)
        }
    }
    Output:
    Map(GfG -> CS portal, Nidhi -> a Geek)
    

    Here, toMap will convert any Traversable to a Map. A Set or a List must have parameters.

  • Size info operations:
    The Size info operations are nonEmpty, isEmpty, hasDefiniteSize, and size. These operations can specify if the given operation is finite or infinite.
    Example :




    // Scala program of Size info operation
      
    // Creating object 
    object Sizeinfo
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a map 
            val x = Map("gfg" -> "cs", "nidhi" -> "geek")
      
            // Applying Size info operation
            val y = x.isEmpty
      
            // Displays true if map is 
            // empty
            println(y)
        }
    }
    Output:
    false
    

    Here, isEmpty checks if the Traversable collection is empty. If the collection of elements is empty then it prints true and if its not empty then it prints false.
    Example :




    // Scala program of Size info operation
      
    // Creating object 
    object Sizeinfo
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a map 
            val x = Map("gfg" -> "cs", "nidhi" -> "geek")
      
            // Applying Size info operation
            val y = x.nonEmpty
      
            // Displays true if map is 
            // not empty
            println(y)
        }
    }
    Output:
    true
    

    Here, nonEmpty checks if the Traversable collection contains elements. If there are elements in the collection then it displays true else false.
    Example :




    // Scala program of Size info operation
      
    // Creating object 
    object Sizeinfo
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a map 
            val q = Map("gfg" -> "cs", "nidhi" -> "geek",
                                        "geeta" -> "coder")
      
            // Applying Size info operation
            val r = q.size
      
            // Displays size of the Map
            println(r)
        }
    }
    Output:
    3
    

    Here, size is utilized to evaluate the size of Traversable collection.
    Example :




    // Scala program of Size info operation
      
    // Creating object 
    object Sizeinfo
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a map 
            val q = Map("gfg" -> "cs", "nidhi" -> "geek",
                                        "geeta" -> "coder")
      
            // Applying Size info operation
            val r = q.hasDefiniteSize
      
            // Displays true if number of
            // elements in Map are finite
            println(r)
        }
    }
    Output:
    true
    

    Here, hasDefiniteSize is utilized to check if the Traversable collection has finite elements or not. If the collection is finite then it returns true else false.

  • Element retrieval operations:
    The Element retrieval operations includes last, head, lastOption, headOption, and find. These operations are utilized to retrieve first or last element of the Traversable collection or to retrieve the first element corresponding to the given condition.
    Example :




    // Scala program of Element 
    // retrieval operation
      
    // Creating object 
    object Retrieval
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a Set of numbers 
            val x = Set(12, 13, 14, 15)
      
            // Applying element retrieval 
            // operation
            val y = x.lastOption
      
            // Displays last element
            // of the Set
            println(y)
        }
    }
    Output:
    Some(15)
    

    Here, last element of the Traversable is returned by lastOption. The stated collection must be ordered, if there are no elements in the collection then None is returned.
    Example :




    // Scala program of Element 
    // retrieval operation
      
    // Creating object 
    object Retrieval
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a Set of numbers 
            val x = Set(12, 13, 14, 15)
      
            // Applying element retrieval 
            // operation
            val y = x.last
      
            // Displays last element
            // of the Set
            println(y)
        }
    }
    Output:
    15
    

    Here, last will return the last element of the stated collection. The collection must be ordered, if its not ordered then some random element is returned.
    Example :




    // Scala program of Element 
    // retrieval operation
      
    // Creating object 
    object Retrieval
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a List of numbers 
            val q = List(12, 24, 36, 48)
      
            // Applying element retrieval 
            // operation
            val r = q.head
      
            // Displays first element
            // of the List
            println(r)
        }
    }
    Output:
    12
    

    Here, head will return first element of the Traversable collection if its ordered and if the collection is not ordered then any random element is returned.
    Example:




    // Scala program of Element 
    // retrieval operation
      
    // Creating object 
    object Retrieval
    {
      
        // Main method
        def main(args: Array[String]) 
        {
      
            // Creating a List of numbers 
            val x = List(8, 10, 21, 17, 29)
      
            // Applying element retrieval 
            // operation 
            val y = x.find(_ % 3 == 0
      
            // Displays first element
            // matching the condition
            println(y)
      
        }
    }
    Output:
    Some(21)
    

    Here, find will retrieve the first element of the collection, which matches the stated condition.
    Example :




    // Scala program of Element 
    // retrieval operation
      
    // Creating object 
    object Retrieval
    {
      
        // Main method
        def main(args: Array[String]) 
        {
          
            // Creating List of numbers 
            val p = List(7, 9, 11, 19, 21)
      
            // Creating a empty List 
            val q = List()
      
            // Applying element retrieval 
            // operation 
            val r = p.headOption 
            val s = q.headOption 
      
            // Displays first element
            // if the List is not empty
            println(r)
            println(s) 
        }
    }
    Output:
    Some(7)
    None
    

    Here, headOption returns first element of an ordered collection but returns None if the collection is empty.

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