Merge branch 'master' of gitlab.com:shockrahwow/csnotes

370/homework/huffman.py

@@ -0,0 +1,133 @@
+import queue
+class Node():
+    def __init__(self, c, weight):
+        self.c = c
+        self.weight = weight
+        self.left = None
+        self.right = None
+  
+    def __repr__(self):
+        return f'{self.c}|{self.weight}'
+
+class MinHeap():
+    def __init__(self):
+        self.data = []
+    
+    def empty(self):
+        return self.size() == 0
+
+    def size(self):
+        return len(self.data)
+
+    def print(self):
+        for x in self.data:
+            print(x.c + str(x.freq))
+
+    def insert(self, val):
+        self.data.append(val)
+        self.__heapifyUp(len(self.data) - 1)
+
+    def extractMin(self):
+        temp = self.data[0]
+        self.__swap(0, -1)    
+        self.data.remove(self.data[-1])
+        self.__heapifyDown(0)
+        return temp
+
+    def __swap(self,i,j):
+        self.data[i], self.data[j] = self.data[j], self.data[i]
+
+    def __heapifyUp(self, idx):
+        if idx > 0:
+            parent = (idx - 1) // 2
+            if (self.data[parent].freq > self.data[idx].freq):
+                self.__swap(parent, idx)
+                self.__heapifyUp(parent)
+    
+    def __heapifyDown(self, idx):
+        data = self.data
+        left = 2 * idx + 1
+        right = 2 * idx + 2
+        mini = idx
+        if (left < len(data) and (data[left].freq < data[mini].freq)):
+            mini = left
+        if (right < len(data) and (data[right].freq < data[mini].freq)):
+            mini = right
+        if (mini is not idx):
+            self.__swap(mini, idx)
+            self.__heapifyDown(mini)
+
+    def printChar(self, c):
+        # Traverse through the tree until we get to a leaf then back out
+        tmp = self.data[0]
+        # keep going until we hit a leaf
+        while tmp.left is not None or tmp.right is not None:
+            # 0 if left : 1 if right
+            continue
+
+
+def main():
+    pq = MinHeap()
+    pq.insert(Node(' ', 1))
+    pq.insert(Node('d', 4))
+    pq.insert(Node('e', 10))
+    pq.insert(Node('i', 13))
+    pq.insert(Node('s', 2))
+    pq.insert(Node('m', 8))
+    pq.insert(Node('o', 6))
+
+
+    assert(list(map(lambda x: x.freq, pq.data)) == [1, 2, 6, 13, 4, 10, 8])
+    assert(pq.extractMin().freq == 1)
+    assert(list(map(lambda x: x.freq, pq.data)) == [2, 4, 6, 13, 8, 10])
+    assert(pq.extractMin().freq == 2)
+    assert(list(map(lambda x: x.freq, pq.data)) == [4, 8, 6, 13, 10])
+    assert(pq.extractMin().freq == 4)
+    pq.print()
+    print("Heap works")
+
+def frequencyMap(string):
+    ret = []
+    for i in string:
+        # check if the node is in our list
+        tmp = [x.c for x in ret]
+        if i not in tmp:
+            ret.append(Node(i, 1))
+        else:
+            # otherwise increment the frequency of that node
+            for k in ret:
+                if k.c == i:
+                    k.weight += 1
+
+    # Sort the charmap based on the frequencies
+    ret.sort(key=lambda x: x.weight)
+    return ret
+
+
+def buildMinHeap(freqs):
+    heap = MinHeap()
+    _queue = queue.Queue()
+    while _queue.qsize() >= 2:
+        left = _queue.get()
+        right = _queue.get()
+        weight = left.weight + right.weight
+        root = Node('*', weight)
+    # Once there is one item in the queue left we can simply return the new thing
+    return heap
+
+
+
+def printEncoding(text, heap):
+    for i in text:
+        heap.printChar(i)
+    
+    print() # newline for the meme
+
+if __name__ == "__main__":
+    text = input()
+    binary = input()
+    # calculate the frequency of each character
+    frequencies = frequencyMap(text)
+    print(frequencies)
+    heap = buildMinHeap(frequencies)
+    printEncoding(binary, heap)

370/homework/input.dat

@@ -0,0 +1,2 @@
+i love computer science
+1100101110101100110111111011100011010101101100100111