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--- pp:scalalab3 [2022/05/25 01:11]
vbadoiu created
+++ pp:scalalab3 [2022/05/25 01:15] (current)
vbadoiu
@@ Line 1: / Line 1: @@
-====== Lab 06. Polymorphism in Scala ======
+====== Lab 11. Polymorphism and For expressions in Scala ======
+=== I. Polymorphism ===
 This lab will start with the implementations discussed during lecture. Please find the polymorphic trait ''FList[A]'' below:
@@ Line 47: / Line 49: @@
   * Can you figure which ones are best implemented in the trait and which in the case classes?
-**6.1.** ''indexOf'' determines the position of a value in the list (starting with 0)
+**1.1.** ''indexOf'' determines the position of a value in the list (starting with 0)
 <code scala>
 def indexOf(e: A): Int
 </code>
-**6.2.** ''update'' creates a new list where the given position is modified with a new value:
+**1.2.** ''update'' creates a new list where the given position is modified with a new value:
 <code scala>
 //Cons(1,Cons(2,Cons(3,FNil()))).update(9,1) = Cons(1,Cons(9,Cons(3,FNil())))
@@ Line 58: / Line 60: @@
 </code>
-**6.3.** ''append'' concatenates this list to another:
+**1.3.** ''append'' concatenates this list to another:
 <code scala>
 def append(l: FList[A]): FList[A]
 </code>
-**6.4.** ''reverse'' returns the reversed list:
+**1.4.** ''reverse'' returns the reversed list:
 <code scala>
 def reverse: FList[A]
 </code>
-**6.5.** ''last'' returns the last element of the list:
+**1.5.** ''last'' returns the last element of the list:
 <code scala>
 def last: A
 </code>
-**6.6.** ''filter'' filters the elements of the list:
+**1.6.** ''filter'' filters the elements of the list:
 <code scala>
 def filter(p: A => Boolean): FList[A]
 </code>
-**6.7.** ''zip'' combines two lists into a list of pairs. If **either** list is larger, the remaining elements are discarded.
+**1.7.** ''zip'' combines two lists into a list of pairs. If **either** list is larger, the remaining elements are discarded.
 <code scala>
 // Cons(1,(Cons(2,Cons(3,FNil()))).zip(Cons(true,Cons(false,Cons(true,FNil())))) =
@@ Line 85: / Line 87: @@
 </code>
-**6.8.** ''insSorted'' inserts an element into a sorted list so that the result is a sorted list.
+**1.8.** ''insSorted'' inserts an element into a sorted list so that the result is a sorted list.
 <code scala>
 def insSorted(f: A => Int)(e: A): FList[A]
 </code>
-**6.9.** ''sortBy'' sorts a list using insertion sort.
+**1.9.** ''sortBy'' sorts a list using insertion sort.
 <code scala>
 def sortBy(f: A => Int): FList[A]
 </code>
-**6.10 (!)** Implement a method ''pack'' which encodes a sorted list as follows:
+**1.10 (!)** Implement a method ''pack'' which encodes a sorted list as follows:
 <code scala>
 [1,1,1,2,3,4,4,5,6].pack = [(1,3),(2,1),(3,1),(4,2),(5,1),(6,1)]
@@ Line 101: / Line 103: @@
 </code>
-====== L07. For expressions ======
+=== II. For expressions ===
-In this lab, we will use matrices to encode Bitmap images. The format is called BPM, and more details are available [[https://en.wikipedia.org/wiki/Netpbm#File_formats|here]]. Our format will be grayscale only. Each pixel of the matrix is encoded as an integer, with values from 0 to 255. Some examples are shown below:
+We will use matrices to encode Bitmap images. The format is called BPM, and more details are available [[https://en.wikipedia.org/wiki/Netpbm#File_formats|here]]. Our format will be grayscale only. Each pixel of the matrix is encoded as an integer, with values from 0 to 255. Some examples are shown below:
 <code>
@@ Line 135: / Line 137: @@
 </code>
-**7.1.** Write a function which converts an image to a string (Hint: you can draw inspiration from a similar one from the lecture):
+**2.1.** Write a function which converts an image to a string (Hint: you can draw inspiration from a similar one from the lecture):
 <code scala>
 def show(m: Img): String = ???
 </code>
-**7.2.** Write a function which performs a horizontal flip on an image. Try to first visualise (you may use pen and paper) how the transformation would look like.
+**2.2.** Write a function which performs a horizontal flip on an image. Try to first visualise (you may use pen and paper) how the transformation would look like.
 <code scala>
 def hFlip(img: Img): Img = ???
 </code>
-**7.3.** Write a function which performs vertical flip.
+**2.3.** Write a function which performs vertical flip.
 <code scala>
 def vFlip(img: Img): Img = ???
 </code>
-**7.4.**  Write a function which performs a 90 degrees rotation to the right. (Hint: you need an ingredient from the lecture. Also, note that there are multiple possible implementations.)
+**2.4.**  Write a function which performs a 90 degrees rotation to the right. (Hint: you need an ingredient from the lecture. Also, note that there are multiple possible implementations.)
 <code scala>
 def rot90Right(img: Img): Img = ???
 </code>
-**7.5.** Write a function which performs a 90 degrees rotation to the left.
+**2.5.** Write a function which performs a 90 degrees rotation to the left.
 <code scala>
 def rot90Left(img: Img): Img = ???
 </code>
-**7.6.** Write a function which inverts an image (values 0 become 255, 1 - 254, and so forth).
+**2.6.** Write a function which inverts an image (values 0 become 255, 1 - 254, and so forth).
-**7.7.** Write a function which crops a given image, using two, two-dimensional coordinates: the higher-left point x and y, and the lower-right point x and y. An example is shown below:
+**2.7.** Write a function which crops a given image, using two, two-dimensional coordinates: the higher-left point x and y, and the lower-right point x and y. An example is shown below:
 <code scala>
 val img = List(List(0,0,1,0,0), List(0,1,0,1,0), List(0,1,1,1,0), List(1,0,0,0,1), List(1,0,0,0,1))
@@ Line 177: / Line 179: @@
 </code>
-**7.8.** Write a function which returns a list of all positions which have pixels of larger intensity than x
+**2.8.** Write a function which returns a list of all positions which have pixels of larger intensity than x
 <code scala>
 def largerPos(img: Img, int: Int): List[(Int,Int)] = ???
 </code>
-**7.9.** Write a function which adds ''x'' to the intensity of each pixel.
+**2.9.** Write a function which adds ''x'' to the intensity of each pixel.
 <code scala>
 def contrast(x: Int)(img: Img): Img = ???
 </code>
-**7.10.** Write a function which takes two images ''X'' and ''Y'' and //glues// them on the horizontal axis (the resulting image will be ''XY'')
+**2.10.** Write a function which takes two images ''X'' and ''Y'' and //glues// them on the horizontal axis (the resulting image will be ''XY'')
 <code scala>
 def hglue(img1: Img, img2: Img): Img = ???
 </code>
-**7.11.** Write a function which takes two images ''X'' and ''Y'' and //glues// them on the vertical axis:
+**2.11.** Write a function which takes two images ''X'' and ''Y'' and //glues// them on the vertical axis:
 <code scala>
 def vglue(img1: Img, img2: Img): Img = ???
 </code>
-**7.12.** Define a function that takes a **square** image, and draws two diagonal lines of intensity 1 across it. Use ''_.until(_)'' and ''_.toList''.
+**2.12.** Define a function that takes a **square** image, and draws two diagonal lines of intensity 1 across it. Use ''_.until(_)'' and ''_.toList''.
 <code scala>
 def diag(img: Img): Img = ???
 </code>
-**7.13.** Define a function which blurs an image as follows:
+**2.13.** Define a function which blurs an image as follows:
   * for each pixel p of intensity > 1: make all neighbouring pixels of intensity 0 equal to p-1 (including diagonals).
   * if some pixel of intensity 0 is in the vicinity of two different >1 pixels of different intensities, the one which is larger should be taken into account
@@ Line 211: / Line 213: @@
 </code>
-**7.14. (!) ** Define a function which builds an effect of intensity x as shown below:
+**2.14. (!) ** Define a function which builds an effect of intensity x as shown below:
 <code scala>
 val img2 = List(