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    Class SingleField

    Field that indexes System.Single values for efficient range filtering and sorting. Here's an example usage:

    document.Add(new SingleField(name, 6.0F, Field.Store.NO));
    For optimal performance, re-use the SingleField and Document instance for more than one document:
        FloatField field = new SingleField(name, 0.0F, Field.Store.NO);
        Document document = new Document();
        document.Add(field);
    
        for (all documents) 
        {
            ...
            field.SetSingleValue(value)
            writer.AddDocument(document);
            ...
        }
    See also Int32Field, Int64Field, DoubleField.

    To perform range querying or filtering against a SingleField, use NumericRangeQuery<T> or NumericRangeFilter<T>. To sort according to a SingleField, use the normal numeric sort types, eg SINGLE. SingleField values can also be loaded directly from IFieldCache.

    You may add the same field name as an SingleField 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 SingleField.

    A SingleField 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 create a custom FieldType and invoke the NumericPrecisionStep setter 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 System.Int32.MaxValue, which produces one term per value.

    For more information on the internals of numeric trie indexing, including the PrecisionStep 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 System.Int32.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 was FloatField in Lucene

    @since 2.9

    Inheritance
    System.Object
    Field
    SingleField
    Implements
    IIndexableField
    Inherited Members
    Field.m_type
    Field.m_name
    Field.FieldsData
    Field.m_tokenStream
    Field.m_boost
    Field.GetStringValue()
    Field.GetStringValue(IFormatProvider)
    Field.GetStringValue(String)
    Field.GetStringValue(String, IFormatProvider)
    Field.GetReaderValue()
    Field.GetTokenStreamValue()
    Field.SetStringValue(String)
    Field.SetReaderValue(TextReader)
    Field.SetBytesValue(BytesRef)
    Field.SetBytesValue(Byte[])
    Field.SetByteValue(Byte)
    Field.SetInt16Value(Int16)
    Field.SetInt32Value(Int32)
    Field.SetInt64Value(Int64)
    Field.SetSingleValue(Single)
    Field.SetDoubleValue(Double)
    Field.SetTokenStream(TokenStream)
    Field.Name
    Field.Boost
    Field.GetNumericValue()
    Field.NumericType
    Field.GetByteValue()
    Field.GetInt16Value()
    Field.GetInt32Value()
    Field.GetInt64Value()
    Field.GetSingleValue()
    Field.GetDoubleValue()
    Field.GetBinaryValue()
    Field.ToString()
    Field.FieldType
    Field.IndexableFieldType
    Field.GetTokenStream(Analyzer)
    Field.TranslateFieldType(Field.Store, Field.Index, Field.TermVector)
    System.Object.Equals(System.Object)
    System.Object.Equals(System.Object, System.Object)
    System.Object.GetHashCode()
    System.Object.GetType()
    System.Object.MemberwiseClone()
    System.Object.ReferenceEquals(System.Object, System.Object)
    Namespace: Lucene.Net.Documents
    Assembly: Lucene.Net.dll
    Syntax
    public sealed class SingleField : Field, IIndexableField

    Constructors

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    SingleField(String, Single, Field.Store)

    Creates a stored or un-stored SingleField with the provided value and default precisionStep PRECISION_STEP_DEFAULT (4).

    Declaration
    public SingleField(string name, float value, Field.Store stored)
    Parameters
    Type Name Description
    System.String name

    field name

    System.Single value

    32-bit System.Single value

    Field.Store stored

    YES if the content should also be stored

    Exceptions
    Type Condition
    System.ArgumentNullException

    if the field name is null.

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    SingleField(String, Single, FieldType)

    Expert: allows you to customize the FieldType.

    Declaration
    public SingleField(string name, float value, FieldType type)
    Parameters
    Type Name Description
    System.String name

    field name

    System.Single value

    32-bit System.Single value

    FieldType type

    customized field type: must have NumericType of SINGLE.

    Exceptions
    Type Condition
    System.ArgumentNullException

    if the field name or type is NONE

    System.ArgumentException

    if the field type does not have a SINGLE NumericType

    Fields

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    TYPE_NOT_STORED

    Type for a SingleField that is not stored: normalization factors, frequencies, and positions are omitted.

    Declaration
    public static readonly FieldType TYPE_NOT_STORED
    Field Value
    Type Description
    FieldType
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    TYPE_STORED

    Type for a stored SingleField: normalization factors, frequencies, and positions are omitted.

    Declaration
    public static readonly FieldType TYPE_STORED
    Field Value
    Type Description
    FieldType

    Implements

    IIndexableField

    Extension Methods

    IndexableFieldExtensions.GetByteValueOrDefault(IIndexableField)
    IndexableFieldExtensions.GetInt16ValueOrDefault(IIndexableField)
    IndexableFieldExtensions.GetInt32ValueOrDefault(IIndexableField)
    IndexableFieldExtensions.GetInt64ValueOrDefault(IIndexableField)
    IndexableFieldExtensions.GetSingleValueOrDefault(IIndexableField)
    IndexableFieldExtensions.GetDoubleValueOrDefault(IIndexableField)
    Number.IsNumber(Object)
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