Python LZW 算法 | 菜鸟教程

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