1 

     2 // first test 

     3 

     4 

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

     6   ratings.groupBy(_._1).mapValues(_.map(_._2)) 

     7 

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

     9   import io.Source

    10   import scala.util._

    11   val csv = Source.fromFile(name)

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

    13 }

    14 

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

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

    17        if (cols(2).toFloat >= 4)) yield (cols(0), cols(1))  

    18 }

    19 

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

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

    22 }

    23 

    24 

    25 val urban_good_ratings = process_ratings(urban_get_csv_file("ratings.csv"))

    26 val urban_movie_names = process_movies(urban_get_csv_file("movies.csv")).toMap

    27 

    28 val urban_ratings_map = urban_groupById(urban_good_ratings)

    29 

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

    31   recommendations(urban_ratings_map, urban_movie_names, n).length

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

    33