diff -r 7a5ad01a85b5 -r 5616b45d656f main_testing2/danube_test7.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main_testing2/danube_test7.scala	Mon Nov 30 00:06:15 2020 +0000
@@ -0,0 +1,48 @@
+
+import CW7b._
+
+// first test 
+
+def urban_groupById(ratings: List[(String, String)], 
+              m: Map[String, List[String]]) : Map[String, List[String]] = ratings match {
+  case Nil => m
+  case (id, mov) :: rest => {
+    val old_ratings = m.getOrElse (id, Nil)
+    val new_ratings = m + (id -> (mov :: old_ratings))
+    urban_groupById(rest, new_ratings)
+  }
+}
+//def urban_groupById(ratings: List[(String, String)]) = 
+//  ratings.groupBy(_._1).view.mapValues(_.map(_._2)).toMap 
+
+def urban_get_csv_file(name: String) : List[String] = {
+  import io.Source
+  import scala.util._
+  val csv = Source.fromFile(name)("ISO-8859-1")
+  csv.mkString.split("\n").toList.drop(1)
+}
+
+def urban_process_ratings(lines: List[String]) : List[(String, String)] = {
+  for (cols <- lines.map(_.split(",").toList); 
+       if (cols(2).toInt >= 4)) yield (cols(0), cols(1))  
+}
+
+def urban_process_movies(lines: List[String]) : List[(String, String)] = {
+  for (cols <- lines.map(_.split(",").toList)) yield (cols(0), cols(1))  
+}
+
+
+val urban_good_ratings = urban_process_ratings(urban_get_csv_file("ratings.csv"))
+val urban_movie_names = urban_process_movies(urban_get_csv_file("movies.csv"))
+
+val urban_movie_names_map = urban_movie_names.toMap
+val urban_ratings_map = urban_groupById(urban_good_ratings, Map())
+//val urban_ratings_map = groupById(urban_good_ratings, Map())
+
+val urban_ratings_map2 =  for ((k, v) <- urban_ratings_map) yield (k, v.take(2))
+
+assert(most_recommended(urban_ratings_map2, urban_movie_names_map).take(3) == 
+       List(("M*A*S*H (a.k.a. MASH) (1970)",15), 
+            ("Star Trek: First Contact (1996)",10), 
+            ("Inception (2010)",9)))
+