ShannonFanokoodaus

ShannonFanokoodaus, often referred to as Shannon-Fano coding, is a type of lossless data compression algorithm. It was developed by Claude Shannon and Robert Fano in the late 1940s. The algorithm works by assigning binary codes to symbols based on their probabilities of occurrence. Symbols that appear more frequently are assigned shorter codes, while less frequent symbols receive longer codes.

The process begins by ordering the symbols according to their probabilities in descending order. Then, the list is recursively divided into two groups such that the sum of probabilities in each group is as close as possible. A '0' is assigned to the codes of symbols in the first group, and a '1' is assigned to the codes of symbols in the second group. This division process continues until each symbol has been assigned a unique binary code.

Shannon-Fano coding is a prefix code, meaning that no code is a prefix of another code. This property ensures that the encoded data can be uniquely decoded. While it was one of the earliest entropy encoding methods, it has largely been superseded by more efficient algorithms like Huffman coding, which generally produces shorter average code lengths for the same set of probabilities. However, Shannon-Fano coding remains historically significant in the development of information theory and data compression.