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 

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

    22 

    23 val urban_ratings_map = urban_groupById(urban_good_ratings)

    24 

    25 assert(favourites(urban_ratings_map, "912").length  == 80)

    26 assert(favourites(urban_ratings_map, "858").length  == 158)

    27 assert(favourites(urban_ratings_map, "260").length  == 201)

    28