diff -r 19b75e899d37 -r 9c03b5e89a2a main_testing2/danube_test3.scala
--- a/main_testing2/danube_test3.scala	Fri Apr 26 17:29:30 2024 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,47 +0,0 @@
-import M2._
-
-
-// first test 
-
-val ls1_urban = List(("1", "a"), ("2", "a"), ("1", "c"), ("2", "a"), ("1", "c"))
-
-val m_urban = groupById(ls1_urban, Map())
-
-assert(m_urban.getOrElse("1", Nil).count(_ == "c") == 2)
-assert(m_urban.getOrElse("1", Nil).count(_ == "a") == 1)
-assert(m_urban.getOrElse("2", Nil) == List("a", "a"))
-
-// second test
-
-def urban_gb(ratings: List[(String, String)]) = 
-  ratings.groupBy(_._1).view.mapValues(_.map(_._2).toSet).toMap 
-
-def urban_gb2(ratings: List[(String, String)]) = 
-  ratings.groupBy(_._1).view.mapValues(_.map(_._2)).toMap 
-
-def urban_ck(ratings: List[(String, String)]) =
-  urban_gb(ratings) == groupById(ratings, Map()).view.mapValues(_.toSet).toMap
-
-
-val ls2_urban = List(("1", "a"), ("1", "b"), ("2", "x"), ("3", "a"), ("2", "y"), ("3", "c"))
-
-assert(urban_ck(ls2_urban))
-
-// thrird test
-
-val ls3_urban = (1 to 1000).map(_.toString).toList
-val ls4_urban = ls3_urban zip ls3_urban.tail
-val ls5_urban = ls4_urban ::: ls4_urban.reverse
-
-assert(urban_ck(ls5_urban))
-
-// fourth test !!!
-
-/*
- 
-val ls6_urban = (10 to 500 by 10).map(_.toString).toList
-val ls7_urban = ls6_urban zip ls6_urban.tail
-val ls8_urban = ls7_urban ::: ls7_urban.reverse
-
-assert(urban_ck(ls8_urban)) 
-*/