diff -r ed63dca8068a -r 4113d4d8cf62 main_marking2/danube_test6.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main_marking2/danube_test6.scala	Mon Jan 25 00:21:00 2021 +0000
@@ -0,0 +1,35 @@
+
+import CW7b._
+
+// first test 
+
+
+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)
+  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).toFloat >= 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 = process_ratings(urban_get_csv_file("ratings.csv"))
+val urban_movie_names = process_movies(urban_get_csv_file("movies.csv")).toMap
+
+val urban_ratings_map = urban_groupById(urban_good_ratings)
+
+assert((for (n <- List("1", "2", "3", "4", "5")) yield {
+  recommendations(urban_ratings_map, urban_movie_names, n).length
+}) == List(2, 2, 2, 0, 2))
+