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Thread: Searching for special file generator

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    Searching for special file generator

    Sorry if theme is offtopic.

    I need file generator with adjustable entropy level to test LZ-based algorithms.
    All generators i've found generate null-filled (highly compressed) or random (uncompressed) data. There is http://cs.fit.edu/~mmahoney/compression/uiq/ too, and files, generated with it are compressed with Deflate at ~1.6 ratio. But entropy level of UIQ is not adjustable and it it very slow - 3 mb\sec at best, i need at least 20 mb\sec.
    Does anyone know about such an utility? I'll be very pleased to have a copy Thanks.

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    Programmer Bulat Ziganshin's Avatar
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    what's an entropy level? are you heard about data models?

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    I am not a programmer, just lamer So i have no info about data models or some other scary words I just need tool which will generate files with some probable comression ratio. I am talking about Deflate algorithm now. And i have utility which shows me order-0 and order-1 entropy for any file, that's enough for me order-0 mark (0 to has rather good correspondence with real life

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    Programmer Bulat Ziganshin's Avatar
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    in that case i recommend you to use samples of real data. Matt's data generation approach is invalid by construction

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    Administrator Shelwien's Avatar
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    Here I just written one:
    http://ctxmodel.net/files/lzgen_v0.rar

    Code:
    LZ77 garbage generator v0
    
    Usage:
     lzgen <bufsize> <coef> <source> <output>
     Generates a file <output> of size bufsize-filesize(source)
     with random data controlled by <coef>.
    
    Examples:
    
    output.rar 
    281292     lzgen 4 1   BOOK1 output
    397729     lzgen 4 50  BOOK1 output
    443992     lzgen 4 100 BOOK1 output
    463524     lzgen 4 200 BOOK1 output
    587929     lzgen 4 900 BOOK1 output

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    Thank you, Eugene! I appreciate your help.

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