This class provides a Field that enables indexing of numeric values for efficient range filtering and sorting. Here's an example usage, adding an int value: More...

Inherits Lucene.Net.Documents.AbstractField.

Public Member Functions
	NumericField (System.String name)
	Creates a field for numeric values using the default `precisionStep` NumericUtils.PRECISION_STEP_DEFAULT (4). The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods. This constructor creates an indexed, but not stored field.

	NumericField (System.String name, Field.Store store, bool index)
	Creates a field for numeric values using the default `precisionStep` NumericUtils.PRECISION_STEP_DEFAULT (4). The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods.

	NumericField (System.String name, int precisionStep)
	Creates a field for numeric values with the specified `precisionStep`. The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods. This constructor creates an indexed, but not stored field.

	NumericField (System.String name, int precisionStep, Field.Store store, bool index)
	Creates a field for numeric values with the specified `precisionStep`. The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods.

override byte[]	GetBinaryValue (byte[] result)
	Returns always `null` for numeric fields

NumericField	SetLongValue (long value_Renamed)
	Initializes the field with the supplied `long` value.

NumericField	SetIntValue (int value_Renamed)
	Initializes the field with the supplied `int` value.

NumericField	SetDoubleValue (double value_Renamed)
	Initializes the field with the supplied `double` value.

NumericField	SetFloatValue (float value_Renamed)
	Initializes the field with the supplied `float` value.

Public Member Functions inherited from Lucene.Net.Documents.AbstractField
virtual byte[]	GetBinaryValue ()
	Return the raw byte[] for the binary field. Note that you must also call BinaryLength and BinaryOffset to know which range of bytes in this returned array belong to the field.

override System.String	ToString ()
	Prints a Field for human consumption.

Properties
override TokenStream	TokenStreamValue `[get]`
	Returns a NumericTokenStream for indexing the numeric value.

override TextReader	ReaderValue `[get]`
	Returns always `null` for numeric fields

override string	StringValue `[get]`
	Returns the numeric value as a string (how it is stored, when Field.Store.YES is chosen).

ValueType	NumericValue `[get]`
	Returns the current numeric value as a subclass of Number, `null` if not yet initialized.

Properties inherited from Lucene.Net.Documents.AbstractField
virtual float	Boost `[get, set]`
	Gets or sets the boost factor for hits for this field.

virtual string	Name `[get]`
	Returns the name of the field as an interned string. For example "date", "title", "body", ...

bool	IsStored `[get]`
	True iff the value of the field is to be stored in the index for return with search hits. It is an error for this to be true if a field is Reader-valued.

bool	IsIndexed `[get]`
	True iff the value of the field is to be indexed, so that it may be searched on.

bool	IsTokenized `[get]`
	True iff the value of the field should be tokenized as text prior to indexing. Un-tokenized fields are indexed as a single word and may not be Reader-valued.

bool	IsTermVectorStored `[get]`
	True iff the term or terms used to index this field are stored as a term vector, available from Lucene.Net.Index.IndexReader.GetTermFreqVector(int,String). These methods do not provide access to the original content of the field, only to terms used to index it. If the original content must be preserved, use the `stored` attribute instead.

virtual bool	IsStoreOffsetWithTermVector `[get]`
	True iff terms are stored as term vector together with their offsets (start and end position in source text).

virtual bool	IsStorePositionWithTermVector `[get]`
	True iff terms are stored as term vector together with their token positions.

bool	IsBinary `[get]`
	True iff the value of the filed is stored as binary

virtual int	BinaryLength `[get]`
	Returns length of byte[] segment that is used as value, if Field is not binary returned value is undefined

virtual int	BinaryOffset `[get]`
	Returns offset into byte[] segment that is used as value, if Field is not binary returned value is undefined

virtual bool	OmitNorms `[get, set]`
	True if norms are omitted for this indexed field

virtual bool	OmitTermFreqAndPositions `[get, set]`
	Expert:

virtual bool	IsLazy `[get]`

abstract TokenStream	TokenStreamValue `[get]`

abstract TextReader	ReaderValue `[get]`

abstract string	StringValue `[get]`

Properties inherited from Lucene.Net.Documents.IFieldable
float	Boost `[get, set]`
	Gets or sets the boost factor for hits for this field. This value will be multiplied into the score of all hits on this this field of this document.

string	Name `[get]`
	Returns the name of the field as an interned string. For example "date", "title", "body", ...

string	StringValue `[get]`
	The value of the field as a String, or null. For indexing, if isStored()==true, the stringValue() will be used as the stored field value unless isBinary()==true, in which case GetBinaryValue() will be used.

TextReader	ReaderValue `[get]`
	The value of the field as a Reader, which can be used at index time to generate indexed tokens.

TokenStream	TokenStreamValue `[get]`
	The TokenStream for this field to be used when indexing, or null.

bool	IsStored `[get]`
	True if the value of the field is to be stored in the index for return with search hits.

bool	IsIndexed `[get]`
	True if the value of the field is to be indexed, so that it may be searched on.

bool	IsTokenized `[get]`
	True if the value of the field should be tokenized as text prior to indexing. Un-tokenized fields are indexed as a single word and may not be Reader-valued.

bool	IsTermVectorStored `[get]`
	True if the term or terms used to index this field are stored as a term vector, available from Lucene.Net.Index.IndexReader.GetTermFreqVector(int,String). These methods do not provide access to the original content of the field, only to terms used to index it. If the original content must be preserved, use the `stored` attribute instead.

bool	IsStoreOffsetWithTermVector `[get]`
	True if terms are stored as term vector together with their offsets (start and end positon in source text).

bool	IsStorePositionWithTermVector `[get]`
	True if terms are stored as term vector together with their token positions.

bool	IsBinary `[get]`
	True if the value of the field is stored as binary

bool	OmitNorms `[get, set]`
	True if norms are omitted for this indexed field.

bool	IsLazy `[get]`
	Indicates whether a Field is Lazy or not. The semantics of Lazy loading are such that if a Field is lazily loaded, retrieving it's values via StringValue() or GetBinaryValue() is only valid as long as the Lucene.Net.Index.IndexReader that retrieved the Document is still open.

int	BinaryOffset `[get]`
	Returns offset into byte[] segment that is used as value, if Field is not binary returned value is undefined

int	BinaryLength `[get]`
	Returns length of byte[] segment that is used as value, if Field is not binary returned value is undefined

bool	OmitTermFreqAndPositions `[get, set]`

Detailed Description

This class provides a Field that enables indexing of numeric values for efficient range filtering and sorting. Here's an example usage, adding an int value:

document.add(new NumericField(name).setIntValue(value));

For optimal performance, re-use the NumericField and Document instance for more than one document:

NumericField field = new NumericField(name); Document document = new Document(); document.add(field);

for(all documents) { ... field.setIntValue(value) writer.addDocument(document); ... }

The .Net native types int, long, float and double are directly supported. However, any value that can be converted into these native types can also be indexed. For example, date/time values represented by a System.DateTime can be translated into a long value using the java.util.Date.getTime method. If you don't need millisecond precision, you can quantize the value, either by dividing the result of java.util.Date.getTime or using the separate getters (for year, month, etc.) to construct an int or long value.

To perform range querying or filtering against a NumericField, use NumericRangeQuery{T} or NumericRangeFilter{T} . To sort according to a NumericField, use the normal numeric sort types, eg SortField.INT NumericField values can also be loaded directly from FieldCache.

By default, a NumericField's value is not stored but is indexed for range filtering and sorting. You can use the NumericField(String,Field.Store,bool) constructor if you need to change these defaults.

You may add the same field name as a NumericField to the same document more than once. Range querying and filtering will be the logical OR of all values; so a range query will hit all documents that have at least one value in the range. However sort behavior is not defined. If you need to sort, you should separately index a single-valued NumericField.

A NumericField will consume somewhat more disk space in the index than an ordinary single-valued field. However, for a typical index that includes substantial textual content per document, this increase will likely be in the noise.

Within Lucene, each numeric value is indexed as a trie structure, where each term is logically assigned to larger and larger pre-defined brackets (which are simply lower-precision representations of the value). The step size between each successive bracket is called the precisionStep, measured in bits. Smaller precisionStep values result in larger number of brackets, which consumes more disk space in the index but may result in faster range search performance. The default value, 4, was selected for a reasonable tradeoff of disk space consumption versus performance. You can use the expert constructor NumericField(String,int,Field.Store,bool) if you'd like to change the value. Note that you must also specify a congruent value when creating NumericRangeQuery{T} or NumericRangeFilter{T}. For low cardinality fields larger precision steps are good. If the cardinality is < 100, it is fair to use int.MaxValue, which produces one term per value.

For more information on the internals of numeric trie indexing, including the precisionStep configuration, see NumericRangeQuery{T}. The format of indexed values is described in NumericUtils.

If you only need to sort by numeric value, and never run range querying/filtering, you can index using a precisionStep of int.MaxValue. This will minimize disk space consumed.

More advanced users can instead use NumericTokenStream directly, when indexing numbers. This class is a wrapper around this token stream type for easier, more intuitive usage.

NOTE: This class is only used during indexing. When retrieving the stored field value from a Document instance after search, you will get a conventional IFieldable instance where the numeric values are returned as Strings (according to toString(value) of the used data type).

<font color="red">NOTE: This API is experimental and might change in incompatible ways in the next release.</font>

Definition at line 145 of file NumericField.cs.

Constructor & Destructor Documentation

Lucene.Net.Documents.NumericField.NumericField ( System.String name )

Creates a field for numeric values using the default precisionStep NumericUtils.PRECISION_STEP_DEFAULT (4). The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods. This constructor creates an indexed, but not stored field.

Parameters

name	the field name

Definition at line 158 of file NumericField.cs.

Lucene.Net.Documents.NumericField.NumericField	(	System.String	name,
		Field.Store	store,
		bool	index
	)

Creates a field for numeric values using the default precisionStep NumericUtils.PRECISION_STEP_DEFAULT (4). The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods.

Parameters

name	the field name
store	if the field should be stored in plain text form (according to `toString(value)` of the used data type)
index	if the field should be indexed using NumericTokenStream

Definition at line 174 of file NumericField.cs.

Lucene.Net.Documents.NumericField.NumericField	(	System.String	name,
		int	precisionStep
	)

Creates a field for numeric values with the specified precisionStep. The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods. This constructor creates an indexed, but not stored field.

Parameters

name	the field name
precisionStep	the used precision step

Definition at line 188 of file NumericField.cs.

Lucene.Net.Documents.NumericField.NumericField	(	System.String	name,
		int	precisionStep,
		Field.Store	store,
		bool	index
	)

Creates a field for numeric values with the specified precisionStep. The instance is not yet initialized with a numeric value, before indexing a document containing this field, set a value using the various set???Value() methods.

Parameters

name	the field name
precisionStep	the used precision step
store	if the field should be stored in plain text form (according to `toString(value)` of the used data type)
index	if the field should be indexed using NumericTokenStream

Definition at line 206 of file NumericField.cs.

Member Function Documentation

override byte [] Lucene.Net.Documents.NumericField.GetBinaryValue ( byte[] result )

virtual

Returns always null for numeric fields

Reimplemented from Lucene.Net.Documents.AbstractField.

Definition at line 219 of file NumericField.cs.

NumericField Lucene.Net.Documents.NumericField.SetDoubleValue ( double value_Renamed )

Initializes the field with the supplied double value.

Parameters

value_Renamed the numeric value

Returns: this instance, because of this you can use it the following way: document.add(new NumericField(name, precisionStep).setDoubleValue(value))

Definition at line 274 of file NumericField.cs.

NumericField Lucene.Net.Documents.NumericField.SetFloatValue ( float value_Renamed )

Initializes the field with the supplied float value.

Parameters

value_Renamed the numeric value

Returns: this instance, because of this you can use it the following way: document.add(new NumericField(name, precisionStep).setFloatValue(value))

Definition at line 287 of file NumericField.cs.

NumericField Lucene.Net.Documents.NumericField.SetIntValue ( int value_Renamed )

Initializes the field with the supplied int value.

Parameters

value_Renamed the numeric value

Returns: this instance, because of this you can use it the following way: document.add(new NumericField(name, precisionStep).setIntValue(value))

Definition at line 261 of file NumericField.cs.

NumericField Lucene.Net.Documents.NumericField.SetLongValue ( long value_Renamed )

Initializes the field with the supplied long value.

Parameters

value_Renamed the numeric value

Returns: this instance, because of this you can use it the following way: document.add(new NumericField(name, precisionStep).SetLongValue(value))

Definition at line 248 of file NumericField.cs.

Property Documentation

ValueType Lucene.Net.Documents.NumericField.NumericValue

get

Returns the current numeric value as a subclass of Number, null if not yet initialized.

Definition at line 238 of file NumericField.cs.

override TextReader Lucene.Net.Documents.NumericField.ReaderValue

get

Returns always null for numeric fields

Definition at line 226 of file NumericField.cs.

override string Lucene.Net.Documents.NumericField.StringValue

get

Returns the numeric value as a string (how it is stored, when Field.Store.YES is chosen).

Definition at line 232 of file NumericField.cs.

override TokenStream Lucene.Net.Documents.NumericField.TokenStreamValue

get

Returns a NumericTokenStream for indexing the numeric value.

Definition at line 214 of file NumericField.cs.

The documentation for this class was generated from the following file:

core/Document/NumericField.cs

Public Member Functions

Properties

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Property Documentation