1 

     2 // first test 

     3 

     4 import M2._

     5 

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

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

     8 

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

    10   import io.Source

    11   import scala.util._

    12   val csv = Source.fromFile(name)

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

    14 }

    15 

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

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

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

    19 }

    20 

    21 

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

    23 

    24 val urban_ratings_map = urban_groupById(urban_good_ratings)

    25 

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

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

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

    29