Package it.unimi.dsi.sux4j.mph.codec

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.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	Codec.Huffman.Coder

Nested classes/interfaces inherited from interface it.unimi.dsi.sux4j.mph.codec.Codec

Codec.Binary, Codec.Decoder, Codec.Gamma, Codec.Huffman, Codec.Unary, Codec.ZeroCodec

Constructor Summary

Constructors

Constructor	Description
Huffman()	Creates a new Huffman codec no length limitations.
Huffman(int maxDecodingTableLength)	Creates a new Huffman codec with specified limit and entropy threshold equal to 0.999.
Huffman(int maxDecodingTableLength, double entropyThreshold)	Creates a new Huffman codec with specified limit and entropy threshold.

Method Summary

Modifier and Type	Method	Description
Codec.Huffman.Coder	getCoder(Long2LongMap frequencies)	Returns a coder for a specific map from symbols to frequencies.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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(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.