org.apache.solr.update.processor

Class TextProfileSignature

java.lang.Object

org.apache.solr.update.processor.Signature

org.apache.solr.update.processor.MD5Signature

org.apache.solr.update.processor.TextProfileSignature

public class TextProfileSignature
extends MD5Signature

This implementation is copied from Apache Nutch.

An implementation of a page signature. It calculates an MD5 hash of a plain text "profile" of a page.

The algorithm to calculate a page "profile" takes the plain text version of a page and performs the following steps:

• remove all characters except letters and digits, and bring all characters to lower case,
• split the text into tokens (all consecutive non-whitespace characters),
• discard tokens equal or shorter than MIN_TOKEN_LEN (default 2 characters),
• sort the list of tokens by decreasing frequency,
• round down the counts of tokens to the nearest multiple of QUANT (QUANT = QUANT_RATE * maxFreq, where QUANT_RATE is 0.01f by default, and maxFreq is the maximum token frequency). If maxFreq is higher than 1, then QUANT is always higher than 2 (which means that tokens with frequency 1 are always discarded).
• tokens, which frequency after quantization falls below QUANT, are discarded.
• create a list of tokens and their quantized frequency, separated by spaces, in the order of decreasing frequency.

This list is then submitted to an MD5 hash calculation.

Constructor Summary

Constructors

Constructor and Description
TextProfileSignature()

Method Summary

Modifier and Type	Method and Description
void	add(String content)
byte[]	getSignature()
void	init(SolrParams params)

Methods inherited from class java.lang.Object

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

Constructor Detail

TextProfileSignature

public TextProfileSignature()

Method Detail

init

public void init(SolrParams params)

Overrides:

init in class Signature

getSignature

public byte[] getSignature()

Overrides:

getSignature in class MD5Signature

add

public void add(String content)

Overrides:

add in class MD5Signature