![]() ![]() Sorry, I did not fully read Fano's paper. This description is based on the description from Wikipedia. But my question is about the algorithm published by Fano which usually is called Shannon-Fano-Coding. Hoffman Coding is more efficient than its two predecessors and it is still used today. Huffman published an even better version in his paper A Method for the Construction of Minimum-Redundancy Codes. 3 years after Fano (in September 1952) his student David A. Fano published an improved version of Shannons algorithm in the paper The Transmission of Information. But Shannon's algorithm was so weak, that under certain circumstances the "compressed" messages could be even longer than in fix length coding. And he also proposed an entropy based data compression algorithm in this paper. In this paper he invented the term bit as we know it today and he also defined what we call Shannon entropy today. Shannon published his famous paper A Mathematical Theory of Communication in July 1948. Is the Shannon-Fano coding as described in Fano's paper The Transmission of Information (1952) really ambiguous? In Detail:Ĭlaude E. This first part was already been implemented using this line of codes. Then from there convert it to Hex value Base64 which is the output is. Here is the resulting Histogram ASTM frame sent :Īs explained in above details, what I want to do is backwards. The thresholds data are then sent using their corresponding ASCII character Here is the output frame (Manufacturer frame content) Each conversion results is given here (represented in hexadecimal data) : Threshold compressed data are encoded in ‘base64’ to be transmitted as ASCII characters. Each compression result is given here (represented in hexadecimal data) : Threshold binary data are compressed using the ‘deflate’ algorithm. Their binary representation are (represented in hexadecimal data) : Here's the document that was sent to me by the provider.Īll data are managed as Little Endian IEEE 754 single precision floating numbers. I would like ask for your help on decompressing String back to its original data. PS: I made sure to highlight the term "length" several times to make it clear that at that point in the text I'm talking about the number of characters and not the length in memory, because I noticed in several forums that I read before, that this confusion was making it difficult to reach conclusions. So here's my question, is there any (invertible) way to convert a string into a smaller one, and when I say smaller I mean "with reduced length"? It seems that "Gzip" or "Brotli" doesn't solve the problem. The fact is that, considering the case where I try to save in the database a string that originally (before compression) is larger than the maximum size (length) allowed in the column, when saving in the database, the "data" that goes to the column of the table in question is the result "base 64" string generated after compression and not the reduced size vector (byte array), and I believe the database will refuse the string (base 64) since its length (in the number of characters) is greater than the length of the original string. The strings provided by the system are in JSON format, in practice they are lists of URLs (with tens of thousands of urls), the urls usually have random sequences of characters, so I tried to generate strings as random as possible. Here's the string generator method, in fact it generates completely random strings in a given size range, and I used in the tests characters provided from the 33 ~ 127 values passed to the Convert.ToChar() method. My sample strings don't exactly contain perfect representations of the cases at hand, but I believe they are good enough. ![]()
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