OpenEuphoria

Re: Compression idea

• Posted by Lewis Townsend <keroltarr at HOTMAIL.COM> Jan 23, 2001
• 482 views

Hello Grape_,

>The problem is just how to decide what is a sting of data that belongs in
>the dictionary.

I started writing a compression library based on a "similar"
idea at one time. However, when I got it finished, it didn't
provide very good compression. Don't be discouraged by my lack
of success since your idea is significantly different that my
word "similar" above is a debatable. The similarity however
was that it DID search for repeated strings so that they
could be replaced by something shorter. I don't have the
file available at this computer but I think the search code
was something like this:

sequence source -- is the source string
constant slen = length( source )
integer len -- length of current segment
sequence s -- current segment

for len = 2 to floor( slen/2 ) do -- slen/2 is maximum seg length
  for pos = 1 to slen-len do -- try every segment in the source
    s = source[pos..pos+len] -- extract segment
    if match( s, source[pos+len..slen] ) -- is there any more of it?
      --this is a repeated string
    end if
  end for
end for

I hope this is somehow helpful as it is completely un-tested.

later,
Lewis Townsend
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