Class Codec.Huffman

java.lang.Object
it.unimi.dsi.sux4j.mph.codec.Codec.Huffman
All Implemented Interfaces:
Codec
Enclosing interface:
Codec
public static class Codec.Huffman extends Object implements Codec
A Huffman codec with length-limiting capabilities and a fast canonical decoder.
Author:
Sebastiano Vigna, Marco Genuzio

  • Constructor Details

    • Huffman

      public Huffman(int maxDecodingTableLength, double entropyThreshold)
      Creates a new Huffman codec with specified limit and entropy threshold.
      Parameters:
      maxDecodingTableLength - a hard limit for the length of the decoding table.
      entropyThreshold - the decoding table will be truncated if the accumulated entropy (starting from the most frequent symbols) exceeds this fraction of the overall entropy.

    • Huffman

      public Huffman(int maxDecodingTableLength)
      Creates a new Huffman codec with specified limit and entropy threshold equal to 0.999.
      Parameters:
      maxDecodingTableLength - a hard limit for the length of the decoding table.

    • Huffman

      public Huffman()
      Creates a new Huffman codec no length limitations.

  • Method Details

    • getCoder

      public Codec.Huffman.Coder getCoder(it.unimi.dsi.fastutil.longs.Long2LongMap frequencies)
      Description copied from interface: Codec
      Returns a coder for a specific map from symbols to frequencies.

      Note that even instantaneous codes (such as Codec.Unary) need to know the set of symbols, as the returned coder needs to known the maximum codeword length.

      Specified by:
      getCoder in interface Codec
      Parameters:
      frequencies - a map from symbols (longs) to frequencies (longs).
      Returns:
      a coder for the given map.