Hi,

I have a short question, well basically looking for some inspiration. What I have is a set of strings that i intend to compress using lzt. But before I do that, I was wondering if I could improve the compression by pre-encoding them. In this case what comes into my mind is Hoffman and arithmetic coding but for that i need to preprocess the entire set (or at leas a section) which for my application is not the most optimal way to go.. as an alternative I could go with run-length (and smart delta coding, maybe ?) and this is where my imagination stops.

About the problem: 

String set is usually comes in batches of size 10000  (|S|=10000) 
Alphabet is 3    (|A|=3, A={A,B,C}) 
Size if each string is exactly 63 characters  (|s1| = |s2| = .. = |s_|
+S|| = 63)

[download]

Example: 

ABBCBCAAAAABBCBCACCCAAAAACAAAAABBBBBAAAAABBAAAAAAAABBCCCACCAABC
BCCCBCAACAABBBCAAACCAAAAACAAAAABBBBBAAAAABBAAAAAAAABBCCCACCABBC
ABCCBBBAAAABBABCACABCCCCCCAAAAABBCBBCCCCAAAAAAAAAAAAACCCACCACCC
...

[download]
One can assume a random distribution of characters from Alphabet A = {A, B, C}

Possible solution: 

position in a byte:

1  2 | 3  4  5  6  7  8
A  A | Delta between mismatching consecutive characters

[download]
First two bits can be used to store the alphabet information : 
00  A
01  B
11  C

[download]
Other 6 can be used for RL coding. Which will ultimately consume 1 byte for each mismatching character. Does anyone have a suggestion for a more optimal solution than this one?

Thank you :)

baxy

In reply to How to efficently pack a string of 63 characters by baxy77bax

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