org.apache.lucene.search.suggest.analyzing

Class XAnalyzingSuggester

java.lang.Object

org.apache.lucene.search.suggest.Lookup

org.apache.lucene.search.suggest.analyzing.XAnalyzingSuggester

All Implemented Interfaces:

org.apache.lucene.util.Accountable

Direct Known Subclasses:

XFuzzySuggester

public class XAnalyzingSuggester
extends org.apache.lucene.search.suggest.Lookup

Suggester that first analyzes the surface form, adds the analyzed form to a weighted FST, and then does the same thing at lookup time. This means lookup is based on the analyzed form while suggestions are still the surface form(s).

This can result in powerful suggester functionality. For example, if you use an analyzer removing stop words, then the partial text "ghost chr..." could see the suggestion "The Ghost of Christmas Past". Note that position increments MUST NOT be preserved for this example to work, so you should call the constructor with preservePositionIncrements parameter set to false

If SynonymFilter is used to map wifi and wireless network to hotspot then the partial text "wirele..." could suggest "wifi router". Token normalization like stemmers, accent removal, etc., would allow suggestions to ignore such variations.

When two matching suggestions have the same weight, they are tie-broken by the analyzed form. If their analyzed form is the same then the order is undefined.

There are some limitations:

• A lookup from a query like "net" in English won't be any different than "net " (ie, user added a trailing space) because analyzers don't reflect when they've seen a token separator and when they haven't.
• If you're using StopFilter, and the user will type "fast apple", but so far all they've typed is "fast a", again because the analyzer doesn't convey whether it's seen a token separator after the "a", StopFilter will remove that "a" causing far more matches than you'd expect.
• Lookups with the empty string return no results instead of all results.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	XAnalyzingSuggester.XBuilder

Nested classes/interfaces inherited from class org.apache.lucene.search.suggest.Lookup

org.apache.lucene.search.suggest.Lookup.LookupPriorityQueue, org.apache.lucene.search.suggest.Lookup.LookupResult

Field Summary

Fields

Modifier and Type	Field and Description
static int	END_BYTE Marks end of the analyzed input and start of dedup byte.
static int	EXACT_FIRST Include this flag in the options parameter to #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) to always return the exact match first, regardless of score.
static int	HOLE_CHARACTER
static int	PAYLOAD_SEP
static int	PRESERVE_SEP Include this flag in the options parameter to #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) to preserve token separators when matching.
static int	SEP_LABEL Represents the separation between tokens, if PRESERVE_SEP was specified

Fields inherited from class org.apache.lucene.search.suggest.Lookup

CHARSEQUENCE_COMPARATOR

Constructor Summary

Constructors

Constructor and Description
XAnalyzingSuggester(org.apache.lucene.analysis.Analyzer analyzer) Calls #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) AnalyzingSuggester(analyzer, analyzer, EXACT_FIRST | PRESERVE_SEP, 256, -1)
XAnalyzingSuggester(org.apache.lucene.analysis.Analyzer indexAnalyzer, org.apache.lucene.analysis.Analyzer queryAnalyzer) Calls #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) AnalyzingSuggester(indexAnalyzer, queryAnalyzer, EXACT_FIRST | PRESERVE_SEP, 256, -1)
XAnalyzingSuggester(org.apache.lucene.analysis.Analyzer indexAnalyzer, org.apache.lucene.util.automaton.Automaton queryPrefix, org.apache.lucene.analysis.Analyzer queryAnalyzer, int options, int maxSurfaceFormsPerAnalyzedForm, int maxGraphExpansions, boolean preservePositionIncrements, org.apache.lucene.util.fst.FST<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>> fst, boolean hasPayloads, int maxAnalyzedPathsForOneInput, int sepLabel, int payloadSep, int endByte, int holeCharacter) Creates a new suggester.

Method Summary

Methods

Modifier and Type	Method and Description
void	build(org.apache.lucene.search.suggest.InputIterator iterator)
protected org.apache.lucene.util.automaton.Automaton	convertAutomaton(org.apache.lucene.util.automaton.Automaton a)
static int	decodeWeight(long encoded) cost -> weight
static int	encodeWeight(long value) weight -> cost
Object	get(CharSequence key) Returns the weight associated with an input string, or null if it does not exist.
long	getCount()
protected List<org.apache.lucene.search.suggest.analyzing.FSTUtil.Path<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>>>	getFullPrefixPaths(List<org.apache.lucene.search.suggest.analyzing.FSTUtil.Path<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>>> prefixPaths, org.apache.lucene.util.automaton.Automaton lookupAutomaton, org.apache.lucene.util.fst.FST<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>> fst) Returns all completion paths to initialize the search.
int	getMaxAnalyzedPathsForOneInput()
org.apache.lucene.analysis.TokenStreamToAutomaton	getTokenStreamToAutomaton()
boolean	load(org.apache.lucene.store.DataInput input)
boolean	load(InputStream input)
List<org.apache.lucene.search.suggest.Lookup.LookupResult>	lookup(CharSequence key, Set<org.apache.lucene.util.BytesRef> contexts, boolean onlyMorePopular, int num)
long	ramBytesUsed() Returns byte size of the underlying FST.
boolean	store(org.apache.lucene.store.DataOutput output)
boolean	store(OutputStream output)
Set<org.apache.lucene.util.IntsRef>	toFiniteStrings(org.apache.lucene.analysis.TokenStream stream)

Methods inherited from class org.apache.lucene.search.suggest.Lookup

build, getChildResources, lookup, lookup

Methods inherited from class java.lang.Object

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

Field Detail

EXACT_FIRST

public static final int EXACT_FIRST

Include this flag in the options parameter to #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) to always return the exact match first, regardless of score. This has no performance impact but could result in low-quality suggestions.

See Also:

Constant Field Values

PRESERVE_SEP

public static final int PRESERVE_SEP

Include this flag in the options parameter to #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) to preserve token separators when matching.

See Also:

Constant Field Values

SEP_LABEL

public static final int SEP_LABEL

Represents the separation between tokens, if PRESERVE_SEP was specified

See Also:

Constant Field Values

END_BYTE

public static final int END_BYTE

Marks end of the analyzed input and start of dedup byte.

See Also:

Constant Field Values

PAYLOAD_SEP

public static final int PAYLOAD_SEP

See Also:

Constant Field Values

HOLE_CHARACTER

public static final int HOLE_CHARACTER

See Also:

Constant Field Values

Constructor Detail

XAnalyzingSuggester

public XAnalyzingSuggester(org.apache.lucene.analysis.Analyzer analyzer)

Calls #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) AnalyzingSuggester(analyzer, analyzer, EXACT_FIRST | PRESERVE_SEP, 256, -1)

Parameters:

analyzer - Analyzer that will be used for analyzing suggestions while building the index.

XAnalyzingSuggester

public XAnalyzingSuggester(org.apache.lucene.analysis.Analyzer indexAnalyzer,
                   org.apache.lucene.analysis.Analyzer queryAnalyzer)

Calls #XAnalyzingSuggester(Analyzer,Analyzer,int,int,int,boolean,FST,boolean,int,int,int,int,int) AnalyzingSuggester(indexAnalyzer, queryAnalyzer, EXACT_FIRST | PRESERVE_SEP, 256, -1)

Parameters:

indexAnalyzer - Analyzer that will be used for analyzing suggestions while building the index.

queryAnalyzer - Analyzer that will be used for analyzing query text during lookup

XAnalyzingSuggester

public XAnalyzingSuggester(org.apache.lucene.analysis.Analyzer indexAnalyzer,
                   org.apache.lucene.util.automaton.Automaton queryPrefix,
                   org.apache.lucene.analysis.Analyzer queryAnalyzer,
                   int options,
                   int maxSurfaceFormsPerAnalyzedForm,
                   int maxGraphExpansions,
                   boolean preservePositionIncrements,
                   org.apache.lucene.util.fst.FST<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>> fst,
                   boolean hasPayloads,
                   int maxAnalyzedPathsForOneInput,
                   int sepLabel,
                   int payloadSep,
                   int endByte,
                   int holeCharacter)

Creates a new suggester.

Parameters:

indexAnalyzer - Analyzer that will be used for analyzing suggestions while building the index.

queryAnalyzer - Analyzer that will be used for analyzing query text during lookup

options - see EXACT_FIRST, PRESERVE_SEP

maxSurfaceFormsPerAnalyzedForm - Maximum number of surface forms to keep for a single analyzed form. When there are too many surface forms we discard the lowest weighted ones.

maxGraphExpansions - Maximum number of graph paths to expand from the analyzed form. Set this to -1 for no limit.

Method Detail

ramBytesUsed

public long ramBytesUsed()

Returns byte size of the underlying FST.

getMaxAnalyzedPathsForOneInput

public int getMaxAnalyzedPathsForOneInput()

convertAutomaton

protected org.apache.lucene.util.automaton.Automaton convertAutomaton(org.apache.lucene.util.automaton.Automaton a)

getTokenStreamToAutomaton

public org.apache.lucene.analysis.TokenStreamToAutomaton getTokenStreamToAutomaton()

build

public void build(org.apache.lucene.search.suggest.InputIterator iterator)
           throws IOException

Specified by:

build in class org.apache.lucene.search.suggest.Lookup

Throws:

IOException

store

public boolean store(OutputStream output)
              throws IOException

Overrides:

store in class org.apache.lucene.search.suggest.Lookup

Throws:

IOException

getCount

public long getCount()

Specified by:

getCount in class org.apache.lucene.search.suggest.Lookup

load

public boolean load(InputStream input)
             throws IOException

Overrides:

load in class org.apache.lucene.search.suggest.Lookup

Throws:

IOException

lookup

public List<org.apache.lucene.search.suggest.Lookup.LookupResult> lookup(CharSequence key,
                                                                Set<org.apache.lucene.util.BytesRef> contexts,
                                                                boolean onlyMorePopular,
                                                                int num)

Specified by:

lookup in class org.apache.lucene.search.suggest.Lookup

store

public boolean store(org.apache.lucene.store.DataOutput output)
              throws IOException

Specified by:

store in class org.apache.lucene.search.suggest.Lookup

Throws:

IOException

load

public boolean load(org.apache.lucene.store.DataInput input)
             throws IOException

Specified by:

load in class org.apache.lucene.search.suggest.Lookup

Throws:

IOException

getFullPrefixPaths

protected List<org.apache.lucene.search.suggest.analyzing.FSTUtil.Path<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>>> getFullPrefixPaths(List<org.apache.lucene.search.suggest.analyzing.FSTUtil.Path<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>>> prefixPaths,
                                                                                                                                                                  org.apache.lucene.util.automaton.Automaton lookupAutomaton,
                                                                                                                                                                  org.apache.lucene.util.fst.FST<org.apache.lucene.util.fst.PairOutputs.Pair<Long,org.apache.lucene.util.BytesRef>> fst)
                                                                                                                                                                       throws IOException

Returns all completion paths to initialize the search.

Throws:

IOException

toFiniteStrings

public Set<org.apache.lucene.util.IntsRef> toFiniteStrings(org.apache.lucene.analysis.TokenStream stream)
                                                    throws IOException

Throws:

IOException

get

public Object get(CharSequence key)

Returns the weight associated with an input string, or null if it does not exist. Unsupported in this implementation (and will throw an UnsupportedOperationException).

Parameters:

key - input string

Returns:

the weight associated with the input string, or null if it does not exist.

decodeWeight

public static int decodeWeight(long encoded)

cost -> weight

Parameters:

encoded - Cost

Returns:

Weight

encodeWeight

public static int encodeWeight(long value)

weight -> cost

Parameters:

value - Weight

Returns:

Cost