#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""created on fri jul 27 18:08:26 2018
@author: luogan
"""# 樹節點類構建
class
treenode
(object):
def__init__
(self, data):
self.val = data[0]
self.priority = data[1]
self.leftchild = none
self.rightchild = none
self.code = ""
# 建立樹節點佇列函式
defcreatnodeq
(codes):
q =
for code in codes:
return q
# 為佇列新增節點元素，並保證優先度從大到小排列
defaddq
(queue, nodenew):
if len(queue) == 0:
return [nodenew]
for i in range(len(queue)):
if queue[i].priority >= nodenew.priority:
return queue[:i] + [nodenew] + queue[i:]
return queue + [nodenew]
# 節點佇列類定義
class
nodeqeuen
(object):
def__init__
(self, code):
self.que = creatnodeq(code)
self.size = len(self.que)
defaddnode
(self,node):
self.que = addq(self.que, node)
self.size += 1
defpopnode
(self):
self.size -= 1
return self.que.pop(0)
# 各個字元在字串**現的次數，即計算優先度
deffrechar
(string):
d ={}
for c in string:
ifnot c in d:
d[c] = 1
else:
d[c] += 1
return sorted(d.items(),key=lambda x:x[1])
# 建立哈夫曼樹
defcreathuffmantree
(nodeq):
while nodeq.size != 1:
node1 = nodeq.popnode()
node2 = nodeq.popnode()
r = treenode([none, node1.priority+node2.priority])
r.leftchild = node1
r.rightchild = node2
nodeq.addnode(r)
return nodeq.popnode()
codedic1 = {}
codedic2 = {}
# 由哈夫曼樹得到哈夫曼編碼表
defhuffmancodedic
(head, x):
global codedic, codelist
if head:
huffmancodedic(head.leftchild, x+'0')
head.code += x
if head.val:
codedic2[head.code] = head.val
codedic1[head.val] = head.code
huffmancodedic(head.rightchild, x+'1')
# 字串編碼
deftransencode
(string):
global codedic1
transcode = ""
for c in string:
transcode += codedic1[c]
return transcode
# 字串解碼
deftransdecode
(stringcode):
global codedic2
code = ""
ans = ""
for ch in stringcode:
code += ch
if code in codedic2:
ans += codedic2[code]
code = ""
return ans
# 舉例
string = "aaggdcccdddgfbbbffggddddgggeffddccccddfgaaa"
t = nodeqeuen(frechar(string))
tree = creathuffmantree(t)
huffmancodedic(tree, '')
print(codedic1,codedic2)
a = transencode(string)
print(a)
aa = transdecode(a)
print(aa)
print(string == aa)
posted on 2018-07-27 18:14收藏
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