Package it.unimi.dsi.big.util

Class ShiftAddXorSignedStringMap

java.lang.Object
it.unimi.dsi.fastutil.objects.AbstractObject2LongFunction<CharSequence>
it.unimi.dsi.big.util.ShiftAddXorSignedStringMap
All Implemented Interfaces:
StringMap<CharSequence>, Function<CharSequence,​Long>, Object2LongFunction<CharSequence>, Size64, Serializable, Function<CharSequence,​Long>, ToLongFunction<CharSequence>
@Deprecated
public class ShiftAddXorSignedStringMap
extends AbstractObject2LongFunction<CharSequence>
implements StringMap<CharSequence>, Serializable
Deprecated.
There are much better and faster hash functions.
A string map based on a function signed using Shift-Add-Xor hashes.

A minimal perfect hash function maps a set of string to an initial segment of the natural numbers, but will actually map any string to that segment. By signing each output value with a hash of the string, we get a dictionary-like functionality with a rate error that can be balanced with space occupancy (signatures can go from 1 to Long.SIZE bits).

For the kind of hash we use, see “Performance in practice of string hashing functions”, by M.V. Ramakrishna and Justin Zobel, Proc. of the Fifth International Conference on Database Systems for Advanced Applications, 1997, pages 215−223.

Since:
2.0
Author:
Sebastiano Vigna
See Also:
Serialized Form