Huffman code Assignment 4 KangPil Kim Jin Kim
![Code • def string 2 Chars(str: String): List[Char] = str. to. List • def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-8.jpg "Code • def string 2 Chars(str: String): List[Char] = str. to. List • def")
![Code • def times(chars: List[Char]): List[(Char, Int)] = { // 빈도수 체크 후 Weight](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-9.jpg "Code • def times(chars: List[Char]): List[(Char, Int)] = { // 빈도수 체크 후 Weight")
![Code • def make. Ordered. Leaf. List(freqs: List[(Char, Int)]): List[Leaf] = { freqs. sort.](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-11.jpg "Code • def make. Ordered. Leaf. List(freqs: List[(Char, Int)]): List[Leaf] = { freqs. sort.")
![Code • def combine(trees: List[Code. Tree]): List[Code. Tree] = trees match { case left](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-12.jpg "Code • def combine(trees: List[Code. Tree]): List[Code. Tree] = trees match { case left")
![Code • def until(p: List[Code. Tree]=>Boolean, f: List[Code. Tree]=>List[Code. Tree]) // singleton //combine (trees:](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-13.jpg "Code • def until(p: List[Code. Tree]=>Boolean, f: List[Code. Tree]=>List[Code. Tree]) // singleton //combine (trees:")
![create. Code. Tree (chars: List[Char]): Code. Tree def create. Code. Tree(chars: List[Char]): Code. Tree](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-15.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def create. Code. Tree(chars: List[Char]): Code. Tree")
![create. Code. Tree (chars: List[Char]): Code. Tree Fork(List(a, l, S, c), 5) Leaf(a, 2](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-16.jpg "create. Code. Tree (chars: List[Char]): Code. Tree Fork(List(a, l, S, c), 5) Leaf(a, 2")
![create. Code. Tree (chars: List[Char]): Code. Tree chars: List[Char] Leaf(S, 1) Leaf(c, 1 )](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-17.jpg "create. Code. Tree (chars: List[Char]): Code. Tree chars: List[Char] Leaf(S, 1) Leaf(c, 1 )")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-18.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-19.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-20.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-21.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-22.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-23.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-24.jpg "create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] type Bit = Int … def encode(tree: Code. Tree)(text:](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-25.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] type Bit = Int … def encode(tree: Code. Tree)(text:")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-26.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-27.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-28.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-29.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-30.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-31.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-32.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-33.jpg "encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def")
![decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-34.jpg "decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =")
![decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-35.jpg "decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =")
![decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-36.jpg "decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =")
![decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-37.jpg "decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =")
![decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-38.jpg "decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =")
![decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-39.jpg "decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] =")
![quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] type Code = (Char, List[Bit]) type Code. Table](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-40.jpg "quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] type Code = (Char, List[Bit]) type Code. Table")
![quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] def quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] =](https://slidetodoc.com/presentation_image_h2/f37d6279c028615fed78fc9917bd5579/image-43.jpg "quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] def quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] =")
- Slides: 43
Huffman code Assignment 4 Kang-Pil Kim, Jin Kim
Ex) Huffman (a, l, s, c), 5 0 1 a, 2 (l, s, c), 3 10 11 l, 1 List((s, 1), (c, 1), (l, 1), (a, 2) (s, c), 2 110 111 s, 1 c, 1
Code • abstract class Code. Tree • case class Fork( left: Code. Tree, right: Code. Tree, chars: List[Char], weight: Int) extends Code. Tree • case class Leaf(char: Char, weight: Int) extends Code. Tree
Code • def weight(tree: Code. Tree): Int = tree match { case Fork(_, _, _, w) => w case Leaf(_, w) => w } • def chars(tree: Code. Tree): List[Char] = tree match { case Fork(_, _, cs, _) => cs case Leaf(c, _) => List(c) }
Code • def make. Code. Tree(left: Code. Tree, right: Code. Tree) = Fork( left, right, chars(left) : : : chars(right), weight(left) + weight(right)) (s, a), 2 s, 1 a, 1
Code • def string 2 Chars(str: String): List[Char] = str. to. List • def singleton(trees: List[Code. Tree]): Boolean = trees. size == 1
Code • def times(chars: List[Char]): List[(Char, Int)] = { // 빈도수 체크 후 Weight value생성 def incr(acc: Map[Char, Int], c: Char) = { val count = (acc get c). get. Or. Else(0) + 1 acc + ((c, count)) } (Map[Char, Int]() /: chars)(incr). iterator. to. List } /: => foldleft List(“s”, ”c”, ”a”, ”l”, ”a”) Map((s, 1), (c, 1)) Map((s, 1)) Map() ‘s’ ‘c’
Fold. Left • (xs fold. Left Accumulate) (function) • ‘ 0’ for ‘+’ operator • ‘ 1’ for ‘ *’ operator
Code • def make. Ordered. Leaf. List(freqs: List[(Char, Int)]): List[Leaf] = { freqs. sort. With((f 1, f 2) => f 1. _2 < f 2. _2) // 오름차순 정렬. map((f) => Leaf (f. _1, f. _2)) //각 리스트들의 원소들을 Leaf로 생성 }
Code • def combine(trees: List[Code. Tree]): List[Code. Tree] = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } s, a, 2 s, 1 a, 1 l, 1 Nil
Code • def until(p: List[Code. Tree]=>Boolean, f: List[Code. Tree]=>List[Code. Tree]) // singleton //combine (trees: List[Code. Tree]) : List[Code. Tree] = { } if (p(trees)) trees // if singleton is true else until(p, f)( f(trees) ) // else recursive until()
PATMAT “Scala” string 2 Chars create. Code. Tree quick. Encode convert encode. Bits List(1, 1, 0, 0) decode List(S, c, a, l, a)
create. Code. Tree (chars: List[Char]): Code. Tree def create. Code. Tree(chars: List[Char]): Code. Tree = { until(singleton, combine)( make. Ordered. Leaf. List(times(chars)) ). head } List(S, c, a, l, a) times List((S, 1), (c, 1), (a, 2), (l, 1)) make. Ordered. Leaf. List(Leaf(S, 1), Leaf(c, 1), Leaf(l, 1), Leaf(a, 2)) combine singleton until List( Fork(Leaf(a, 2), Fork(Leaf(l, 1), Fork(Leaf(S, 1), Leaf(c, 1), List(S, c), 2), List(l, S, c), 3), List(a, l, S, c), 5) )
create. Code. Tree (chars: List[Char]): Code. Tree Fork(List(a, l, S, c), 5) Leaf(a, 2 ) Fork(List(l, S, c), 3) Leaf(l, 1 ) Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 )
create. Code. Tree (chars: List[Char]): Code. Tree chars: List[Char] Leaf(S, 1) Leaf(c, 1 ) Leaf(l, 1 ) Leaf(a, 2 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 ) Leaf(l, 1 ) Leaf(a, 2 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } weight=2 Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 ) weight=1 Leaf(l, 1 ) weight=2 Leaf(a, 2 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } weight=1 Leaf(l, 1 ) weight=2 Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 ) weight=2 Leaf(a, 2 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } Fork(List(l, S, c), 3 ) Leaf(l, 1 ) Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 ) Leaf(a, 2 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } weight=3 Fork(List(l, S, c), 3 ) Leaf(l, 1 ) Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 ) weight=2 Leaf(a, 2 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } weight=2 Leaf(a, 2 weight=3 ) Fork(List(l, S, c), 3 ) Leaf(l, 1 ) Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 ) nil
create. Code. Tree (chars: List[Char]): Code. Tree def until(. . ). . { if (p(trees)) trees else until(p, f)( f(trees) ) } def combine(trees: List[Code. Tree])… = trees match { case left : : right : : cs => (make. Code. Tree(left, right) : : cs). sort. With((t 1, t 2) => weight(t 1) < weight(t 2)) case _ => trees } Fork(List(a, l, S, c), 5) Leaf(a, 2 ) nil Fork(List(l, S, c), 3 ) Leaf(l, 1 ) Fork(List(S, c), 2 ) Leaf(S, 1) Leaf(c, 1 )
encode(tree: Code. Tree)(text: List[Char]): List[Bit] type Bit = Int … def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } flat. Map List(S, c, a, l, a) lookup
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } S 1 List(1)
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } S 1 1 List(1, 1)
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } S 1 1 List(1, 1, 0) 0
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } c 1 1 List(1, 1, 1) 1
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } a 0 List(0)
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } l 1 0 List(1, 0)
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } a 0 List(0)
encode(tree: Code. Tree)(text: List[Char]): List[Bit] def encode(tree: Code. Tree)(text: List[Char]): List[Bit] = { def lookup(tree: Code. Tree)(c: Char): List[Bit] = tree match { case Leaf(_, _) => List() case Fork(left, right, _, _) if chars(left). contains(c) => 0 : : lookup(left)(c) case Fork(left, right, _, _) => 1 : : lookup(right)(c) } text flat. Map lookup(tree) } List(S, c, a, l, a) flat. Map lookup List(1, 1, 0), List(1, 1, 1), List(0), List(1, 0), List(0)) List(1, 1, 0, 0)
decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] = { def traverse(remaining: Code. Tree, bits: List[Bit]): List[Char] = remaining match { case Leaf(c, _) if bits. is. Empty => List(c) case Leaf(c, _) => c : : traverse(tree, bits) case Fork(left, right, _, _) if bits. head == 0 => traverse(left, bits. tail) case Fork(left, right, _, _) => traverse(right, bits. tail) } traverse(tree, bits) } List(1, 1, 0, 0) traverse List(S, c, a, l, a)
decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] = { def traverse(remaining: Code. Tree, bits: List[Bit]): List[Char] = remaining match { case Leaf(c, _) if bits. is. Empty => List(c) case Leaf(c, _) => c : : traverse(tree, bits) case Fork(left, right, _, _) if bits. head == 0 => traverse(left, bits. tail) case Fork(left, right, _, _) => traverse(right, bits. tail) } traverse(tree, bits) } List(1, 1, 0, 0)
decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] = { def traverse(remaining: Code. Tree, bits: List[Bit]): List[Char] = remaining match { case Leaf(c, _) if bits. is. Empty => List(c) case Leaf(c, _) => c : : traverse(tree, bits) case Fork(left, right, _, _) if bits. head == 0 => traverse(left, bits. tail) case Fork(left, right, _, _) => traverse(right, bits. tail) } traverse(tree, bits) } List(1, 1, 0, 0)
decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] = { def traverse(remaining: Code. Tree, bits: List[Bit]): List[Char] = remaining match { case Leaf(c, _) if bits. is. Empty => List(c) case Leaf(c, _) => c : : traverse(tree, bits) case Fork(left, right, _, _) if bits. head == 0 => traverse(left, bits. tail) case Fork(left, right, _, _) => traverse(right, bits. tail) } traverse(tree, bits) } List(1, 1, 0, 0)
decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] = { def traverse(remaining: Code. Tree, bits: List[Bit]): List[Char] = remaining match { case Leaf(c, _) if bits. is. Empty => List(c) case Leaf(c, _) => c : : traverse(tree, bits) case Fork(left, right, _, _) if bits. head == 0 => traverse(left, bits. tail) case Fork(left, right, _, _) => traverse(right, bits. tail) } traverse(tree, bits) } List(1, 1, 0, 0) List(S)
decode(tree: Code. Tree, bits: List[Bit]): List[Char] def decode(tree: Code. Tree, bits: List[Bit]): List[Char] = { def traverse(remaining: Code. Tree, bits: List[Bit]): List[Char] = remaining match { case Leaf(c, _) if bits. is. Empty => List(c) case Leaf(c, _) => c : : traverse(tree, bits) case Fork(left, right, _, _) if bits. head == 0 => traverse(left, bits. tail) case Fork(left, right, _, _) => traverse(right, bits. tail) } traverse(tree, bits) } List(1, 1, 0, 0) List(S, c, a, l, a)
quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] type Code = (Char, List[Bit]) type Code. Table = List[(Char, List[Bit])] def quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] = text flat. Map code. Bits(convert(tree)) Code. Table convert List( (a, List(0)), (l, List(1, 0)), (S, List(1, 1, 0)), (c, List(1, 1, 1)) ) flat. Map List(S, c, a, l, a) code. Bits List(1, 1, 0, 0)
convert(tree: Code. Tree): Code. Table def convert(tree: Code. Tree): Code. Table = tree match { case Leaf(c, w) => List( (c, List()) ) case Fork(left, right, cs, w) => merge. Code. Tables(convert(left), convert(right)) } merge. Code. Tables List(a, List()) List(l, List()) List(S, List()) merge. Code. Tables List(c, List())
convert(tree: Code. Tree): Code. Table def convert(tree: Code. Tree): Code. Table = tree match { case Leaf(c, w) => List( (c, List()) ) case Fork(left, right, cs, w) => merge. Code. Tables(convert(left), convert(right)) } def merge. Code. Tables(a: Code. Table, b: Code. Table): Code. Table = { def prepend(b: Bit)(code: Code): Code = (code. _1, b : : code. _2) a. map(prepend(0)) : : : b. map(prepend(1)) } List((a, List(0)), (l, List(1, 0)), (S, List(1, 1, 0)), (c, List(1, 1, 1))) List((l, List(0)), (S, List(1, 0)), (c, List(1, 1))) List(a, List()) List(l, List()) List(S, List()) List((S, List(0)), (c, List(1)) ) List(c, List())
quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] def quick. Encode(tree: Code. Tree)(text: List[Char]): List[Bit] = text flat. Map code. Bits(convert(tree)) def code. Bits(table: Code. Table)(char: Char): List[Bit] = { table. filter( (code) => code. _1 == char ). head. _2 } Code. Table (a, List(0)) (l, List(1, 0)) (S, List(1, 1, 0)) (c, List(1, 1, 1)) ) S List(1, 1, 0) c List(1, 1, 1) a List(0) l List(1, 0) a List(0) List(1, 1, 0, 0 )