Methods to call on a Set in Scala

A set is a collection that only contains unique items. In Scala, both mutable and immutable sets are available. The mutable set is those set in which the value of the object is change, but, in the immutable set, the value of the object is not changed itself. The immutable set is defined under Scala.collection.immutable._ package and mutable set are defined under Scala.collection.mutable._ package. Here, we will discuss some important methods of Scala.collection.immutable._ package. 1. def +(elem: A): Set[A] - This method is used to add an element to the set and then returns it. Example : Output:

Set(1, 6, 9, 2, 7, 8, 4)

2. def -(elem: A): Set[A] - This method is used to remove the element from the set and then returns it. Example : Output:

Set(9, 2, 7, 8, 4)

3. def contains(elem: A): Boolean - This method is return true if the set contains the specified element. Otherwise, it will return false. Example : Output:

true

4. def &(that: Set[A]): Set[A] - This method is used to return an intersection of two sets. Example : Output:

Set(8, 4)

5. def &~(that: Set[A]): Set[A] - This symbol means set difference. Example : Output:

Set(1, 9, 2, 7)

6. def +(elem1: A, elem2: A, elems: A*): Set[A] - This method is used to add the multiple elements to a Scala set and then returns it. Example : Output:

Set(1, 6, 9, 2, 7, 3, 8, 4)

7. def ++(elems: A): Set[A] - This method is used for concatenation of a set with another. Example : Output:

Set(1, 6, 9, 2, 7, 3, 8, 4)

8. def -(elem1: A, elem2: A, elems: A*): Set[A] - This method is used to remove each element mentioned from the set. Example : Output:

Set(9, 2, 7, 4)

9. def addString(b: StringBuilder): StringBuilder - This method is used to add all the elements of the set to the String Builder. Example : Output:

192784

10. def addString(b: StringBuilder, sep: String): StringBuilder - This method is used a separator to the above functionality. Example : Output:

1*9*2*7*8*4

11. def apply(elem: A) - This method is used to checks whether the element is part of the set or not. It returns Boolean value True or False. Example : Output:

true

12. def drop(n: Int): Set[A]] - This method is used to return all elements except the first n. Example : Output:

Set(7, 3, 8)

13. def dropRight(n: Int): Set[A] - This method is used to returns all elements except the last n that is just opposite to the above method(). Example : Output:

Set(5, 1, 9, 2)

14. def equals(that: Any): Boolean - This method is used to compares the set to another sequence. Example : Output:

true

15. def head: A - This method is used to return the first element from the set. Example : Output:

5

16. def init: Set[A] - This method is used to return all elements from the set, except the last. Example : Output:

Set(5, 1, 9, 2, 7)

17. def intersect(that: Set[A]): Set[A] - This method is used to return the intersection of two sets that is it returns the common element from the two sets. Example : Output:

Set(1, 9, 2, 3)

18. def isEmpty: Boolean - This method return true if the given set is empty. Otherwise, it will return False. Example : Output:

false

19. def iterator: Iterator[A] - This method help in creating a new iterator over the set. Example : Output:

non-empty iterator

20. def last: A - This method helps in returning the last element from a set. Example : Output:

3

21. def max: A - This method is used to return the highest value from the set. Example : Output:

8

22. def min: A - This method is used to return the lowest element from the set. Example : Output:

1

23. def mkString: String - This method helps to represents all elements of the set as a String. Example : Output:

52738

24. def product: A - This method is used to return the product of all elements in the set. Example : Output:

1890

25. def size: Int - This method is used to return the size of the set. Example : Output:

5

26. def sum: A - This method is used to return the sum of all elements of the set. Example : Output:

27

27. def tail: Set[A] - This method is used to return all elements of the set except the first. Example : Output:

Set(2, 7, 3, 8)

28. def take(n: Int): Set[A] - This method is used to return the first n elements from the set. Example : Output:

Set(5, 1, 9)

Here are some more methods which are called on a set.

Method	Description
def &(that: Set[A]): Set[A]	This method helps in returning an intersection of two sets.
def count(p: (A) => Boolean): Int	This method is used to return the count of elements that satisfy the predicate.
def diff(that: Set[A]): Set[A]	This method is used to return the set difference(elements existing in one set, but not in another).
def dropWhile(p: (A) => Boolean): Set[A]	This method is used to drop elements until the first element that doesn’t satisfy the predicate.
def exists(p: (A) => Boolean): Boolean	This method is used to return true if predicate holds true else returns false.
def filter(p: (A) => Boolean): Set[A]	This method is used to filter elements.
def find(p: (A) => Boolean): Option[A]	This method is used to return the first element that satisfies the predicate.
def forall(p: (A) => Boolean): Boolean	This method is used to return true if all elements of the set satisfy the predicate. Otherwise, false.
def map[B](f: (A) => B): immutable.Set[B]	This method is used to applies the function to all elements of the set and returns it.
def splitAt(n: Int): (Set[A], Set[A])	This method is used to split the set at the given index and returns the two resulting subsets.
def subsetOf(that: Set[A]): Boolean	This method is used to return true if the set passed as argument is a subset of this set else return false.
def takeRight(n: Int):Set[A]	This method is used to return the last n elements.
def toArray: Array[A]	This method is used to return an Array holding elements from the set.
def toList: List[A]	This method is used to return a List from elements of the set.
def toSeq: Seq[A]	This method is used to return a sequence from the set.
def toString(): String	This method represents the elements of the set as a String.