--- a/pre_solution2/docdiff.scala	Sat Nov 06 00:06:39 2021 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,117 +0,0 @@
-// Preliminary Part about Code Similarity
-//========================================
-
-
-object CW7a { 
-
-//(1) Complete the clean function below. It should find
-//    all words in a string using the regular expression
-//    \w+  and the library function 
-//
-//         some_regex.findAllIn(some_string)
-//
-//    The words should be Returned as a list of strings.
-
-def clean(s: String) : List[String] = 
-  ("""\w+""".r).findAllIn(s).toList
-
-
-//(2) The function occurrences calculates the number of times  
-//    strings occur in a list of strings. These occurrences should 
-//    be calculated as a Map from strings to integers.
-
-def occurrences(xs: List[String]): Map[String, Int] =
-  (for (x <- xs.distinct) yield (x, xs.count(_ == x))).toMap
-
-//(3) This functions calculates the dot-product of two documents
-//    (list of strings). For this it calculates the occurrence
-//    maps from (2) and then multiplies the corresponding occurrences. 
-//    If a string does not occur in a document, the product is zero.
-//    The function finally sums up all products. 
-
-def prod(lst1: List[String], lst2: List[String]) : Int = {
-    val words = (lst1 ::: lst2).distinct
-    val occs1 = occurrences(lst1)
-    val occs2 = occurrences(lst2)
-    words.map{ w => occs1.getOrElse(w, 0) * occs2.getOrElse(w, 0) }.sum
-}          
-
-//(4) Complete the functions overlap and similarity. The overlap of
-//    two documents is calculated by the formula given in the assignment
-//    description. The similarity of two strings is given by the overlap
-//    of the cleaned (see (1)) strings.  
-
-def overlap(lst1: List[String], lst2: List[String]) : Double = {
-    val m1 = prod(lst1, lst1)
-    val m2 = prod(lst2, lst2) 
-    prod(lst1, lst2).toDouble / (List(m1, m2).max)
-}
-
-def similarity(s1: String, s2: String) : Double =
-  overlap(clean(s1), clean(s2))
-
-
-/*
-
-
-val list1 = List("a", "b", "b", "c", "d") 
-val list2 = List("d", "b", "d", "b", "d")
-
-occurrences(List("a", "b", "b", "c", "d"))   // Map(a -> 1, b -> 2, c -> 1, d -> 1)
-occurrences(List("d", "b", "d", "b", "d"))   // Map(d -> 3, b -> 2)
-
-prod(list1,list2) // 7 
-
-overlap(list1, list2)   // 0.5384615384615384
-overlap(list2, list1)   // 0.5384615384615384
-overlap(list1, list1)   // 1.0
-overlap(list2, list2)   // 1.0
-
-// Plagiarism examples from 
-// https://desales.libguides.com/avoidingplagiarism/examples
-
-val orig1 = """There is a strong market demand for eco-tourism in
-Australia. Its rich and diverse natural heritage ensures Australia's
-capacity to attract international ecotourists and gives Australia a
-comparative advantage in the highly competitive tourism industry."""
-
-val plag1 = """There is a high market demand for eco-tourism in
-Australia. Australia has a comparative advantage in the highly
-competitive tourism industry due to its rich and varied natural
-heritage which ensures Australia's capacity to attract international
-ecotourists."""
-
-similarity(orig1, plag1)
-
-
-// Plagiarism examples from 
-// https://www.utc.edu/library/help/tutorials/plagiarism/examples-of-plagiarism.php
-
-val orig2 = """No oil spill is entirely benign. Depending on timing and
-location, even a relatively minor spill can cause significant harm to
-individual organisms and entire populations. Oil spills can cause
-impacts over a range of time scales, from days to years, or even
-decades for certain spills. Impacts are typically divided into acute
-(short-term) and chronic (long-term) effects. Both types are part of a
-complicated and often controversial equation that is addressed after
-an oil spill: ecosystem recovery."""
-
-val plag2 = """There is no such thing as a "good" oil spill. If the
-time and place are just right, even a small oil spill can cause damage
-to sensitive ecosystems. Further, spills can cause harm days, months,
-years, or even decades after they occur. Because of this, spills are
-usually broken into short-term (acute) and long-term (chronic)
-effects. Both of these types of harm must be addressed in ecosystem
-recovery: a controversial tactic that is often implemented immediately
-following an oil spill."""
-
-overlap(clean(orig2), clean(plag2))
-similarity(orig2, plag2)
-
-// The punchline: everything above 0.6 looks suspicious and 
-// should be looked at by staff.
-
-*/
-
-
-}