1 

     2 import M2._

     3 

     4 // first test 

     5 

     6 def urban_groupById(ratings: List[(String, String)], 

     7               m: Map[String, List[String]]) : Map[String, List[String]] = ratings match {

     8   case Nil => m

     9   case (id, mov) :: rest => {

    10     val old_ratings = m.getOrElse (id, Nil)

    11     val new_ratings = m + (id -> (mov :: old_ratings))

    12     urban_groupById(rest, new_ratings)

    13   }

    14 }

    15 

    16 //def urban_groupById(ratings: List[(String, String)]) = 

    17 //  ratings.groupBy(_._1).view.mapValues(_.map(_._2)).toMap 

    18 

    19 def urban_get_csv_file(name: String) : List[String] = {

    20   import io.Source

    21   import scala.util._

    22   val csv = Source.fromFile(name)("ISO-8859-1")

    23   csv.mkString.split("\n").toList.drop(1)

    24 }

    25 

    26 def urban_process_ratings(lines: List[String]) : List[(String, String)] = {

    27   for (cols <- lines.map(_.split(",").toList); 

    28        if (cols(2).toInt >= 4)) yield (cols(0), cols(1))  

    29 }

    30 

    31 def urban_process_movies(lines: List[String]) : List[(String, String)] = {

    32   for (cols <- lines.map(_.split(",").toList)) yield (cols(0), cols(1))  

    33 }

    34 

    35 

    36 val urban_good_ratings = urban_process_ratings(urban_get_csv_file("ratings.csv"))

    37 val urban_movie_names = urban_process_movies(urban_get_csv_file("movies.csv")).toMap

    38 

    39 val urban_ratings_map = urban_groupById(urban_good_ratings, Map())

    40 

    41 assert((for (n <- List("1", "2", "3", "4", "5")) yield {

    42   recommendations(urban_ratings_map, urban_movie_names, n).length

    43 }) == List(2, 2, 2, 0, 2))

    44