Your tasks Implement the methods marked with ??? in frequencies.scala. （as shown in below) (Programming Style Restrictions) (In addition to computing frequencies, we also practice functional programming style in this exercise. Therefore, you are not allowed to use var declarations, Arrays, scala.collection.mutable or java.util data types in this exercise. The val declarations are allowed and even recommended to break down longer sequences of method applications into smaller and more readable parts.) package frequencies: /* * NOTE: this is an exercise on functional programming style. * Therefore, you are NOT allowed to use mutable data structures or vars. */ /** * Given a sequence seq of items of type T, * returns a map that associates each item in the sequence to the number times it * occurs in the sequence. * The resulting map should be undefined for all the items that do not appear in the sequence. * Hint: study the methods of scala.collection.Seq and scala.collection.Map; * For instance, groupBy and map may be useful. */ def frequencies[T](seq: Seq[T]): Map[T, Int] = ??? end frequencies /** * Given a sequence seq of items of type T, * returns a map that associates, to each positive integer i, the set of items * that occur i times in the sequence. * If no item occurs i times in the sequence, then the map must be undefined for that i. */ def freqToItems[T](seq: Seq[T]): Map[Int, Set[T]] = ??? end freqToItems /** * Given a sequence seq of items of type T, * returns the set of all items that occur most frequently in the sequence. * If the sequence is empty, then (and only then) the resulting set should be empty. */ def mostFrequent[T](seq: Seq[T]): Set[T] = ??? end mostFrequent

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Your tasks

Implement the methods marked with ??? in frequencies.scala. （as shown in below)

(Programming Style Restrictions)

(In addition to computing frequencies, we also practice functional programming style in this exercise. Therefore, you are not allowed to use var declarations, Arrays, scala.collection.mutable or java.util data types in this exercise. The val declarations are allowed and even recommended to break down longer sequences of method applications into smaller and more readable parts.)

package frequencies:

* NOTE: this is an exercise on functional programming style.

* Therefore, you are NOT allowed to use mutable data structures or vars.

/**

* Given a sequence seq of items of type T,

* returns a map that associates each item in the sequence to the number times it

* occurs in the sequence.

* The resulting map should be undefined for all the items that do not appear in the sequence.

* Hint: study the methods of scala.collection.Seq and scala.collection.Map;

* For instance, groupBy and map may be useful.

def frequencies[T](seq: Seq[T]): Map[T, Int] =

???

end frequencies

/**

* Given a sequence seq of items of type T,

* returns a map that associates, to each positive integer i, the set of items

* that occur i times in the sequence.

* If no item occurs i times in the sequence, then the map must be undefined for that i.

def freqToItems[T](seq: Seq[T]): Map[Int, Set[T]] =

???

end freqToItems

/**

* Given a sequence seq of items of type T,

* returns the set of all items that occur most frequently in the sequence.

* If the sequence is empty, then (and only then) the resulting set should be empty.

def mostFrequent[T](seq: Seq[T]): Set[T] =

???

end mostFrequent

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