Python LZW 算法

LZW 压缩算法

string = "thisisthe"
dictionary = {chr(i):i for i in range(97,123)}
 
last = 256
p = ""
result = []
 
for c in string:
	pc = p+c
	if pc in dictionary:
		p = pc
	else:
		result.append(dictionary[p])
		dictionary[pc] = last
		last += 1
		p = c
 
if p != '':
	result.append(dictionary[p])
 
print(result)

以上代码运行结果为：

[116, 104, 105, 115, 258, 256, 101]

LZW 解压缩算法

dictionary = {i:chr(i) for i in range(97,123)}
last = 256
arr = [97, 97, 98, 256, 258, 257, 259]
 
result = []
p = arr.pop(0)
result.append(dictionary[p])
 
for c in arr:
	if c in dictionary:
		entry = dictionary[c]
	result.append(entry)
	dictionary[last] = dictionary[p] + entry[0]
	last += 1
	p = c
 
print(''.join(result))

以上代码运行结果为：

aabaabaabaab