Namespace Lucene.Net.Queries.Function.ValueSources

A variety of functions to use with FunctionQuery.

Classes

BoolFunction

Abstract parent class for those ValueSource implementations which apply boolean logic to their values

ByteFieldSource

Obtains field values from the FieldCache using and makes those values available as other numeric types, casting as needed. *

BytesRefFieldSource

An implementation for retrieving FunctionValues instances for based fields.

ConstNumberSource

ConstNumberSource is the base class for all constant numbers

ConstValueSource

ConstValueSource returns a constant for all documents

ValueSource implementation which only returns the values from the provided ValueSources which are available for a particular docId. Consequently, when combined with a ConstValueSource, this function serves as a way to return a default value when the values for a field are unavailable.

DivSingleFunction

Function to divide "a" by "b"

NOTE: This was DivFloatFunction in Lucene

DocFreqValueSource

DocFreqValueSource returns the number of documents containing the term.

This is a Lucene.NET INTERNAL API, use at your own risk

DoubleConstValueSource

Function that returns a constant double value for every document.

DoubleFieldSource

Obtains field values from and makes those values available as other numeric types, casting as needed.

DualSingleFunction

Abstract ValueSource implementation which wraps two ValueSources and applies an extendible function to their values.

NOTE: This was DualFloatFunction in Lucene

EnumFieldSource

Obtains field values from and makes those values available as other numeric types, casting as needed. StrVal of the value is not the value, but its (displayed) value

FieldCacheSource

A base class for ValueSource implementations that retrieve values for a single field from the FieldCache.

IDFValueSource

Function that returns for every document.

Note that the configured Similarity for the field must be a subclass of TFIDFSimilarity @lucene.internal

IfFunction

Depending on the value of the Lucene.Net.Queries.Function.ValueSources.IfFunction.ifSource function, returns the value of the Lucene.Net.Queries.Function.ValueSources.IfFunction.trueSource or Lucene.Net.Queries.Function.ValueSources.IfFunction.falseSource function.

Int16FieldSource

Obtains field values from the FieldCache using and makes those values available as other numeric types, casting as needed.

NOTE: This was ShortFieldSource in Lucene

Int32FieldSource

Obtains field values from and makes those values available as other numeric types, casting as needed.

NOTE: This was IntFieldSource in Lucene

Int64FieldSource

Obtains field values from and makes those values available as other numeric types, casting as needed.

NOTE: This was LongFieldSource in Lucene

JoinDocFreqValueSource

Use a field value and find the Document Frequency within another field.

@since solr 4.0

LinearSingleFunction

LinearSingleFunction implements a linear function over another ValueSource.

Normally Used as an argument to a FunctionQuery

NOTE: This was LinearFloatFunction in Lucene

LiteralValueSource

Pass a the field value through as a , no matter the type // Q: doesn't this mean it's a "str"?

MaxDocValueSource

Returns the value of MaxDoc for every document. This is the number of documents including deletions.

MaxSingleFunction

MaxSingleFunction returns the max of it's components.

NOTE: This was MaxFloatFunction in Lucene

MinSingleFunction

MinSingleFunction returns the min of it's components.

NOTE: This was MinFloatFunction in Lucene

MultiBoolFunction

Abstract ValueSource implementation which wraps multiple ValueSources and applies an extendible function to their values.

MultiFunction

Abstract parent class for ValueSource implementations that wrap multiple ValueSources and apply their own logic.

MultiFunction.Values

MultiSingleFunction

Abstract ValueSource implementation which wraps multiple ValueSources and applies an extendible function to their values.

NOTE: This was MultiFloatFunction in Lucene

MultiValueSource

A ValueSource that abstractly represents ValueSources for poly fields, and other things.

NormValueSource

Function that returns for every document.

Note that the configured Similarity for the field must be a subclass of TFIDFSimilarity @lucene.internal

NumDocsValueSource

Returns the value of NumDocs for every document. This is the number of documents excluding deletions.

OrdFieldSource

Obtains the ordinal of the field value from the default Lucene FieldCache using StringIndex.

The native lucene index order is used to assign an ordinal value for each field value.

Field values (terms) are lexicographically ordered by unicode value, and numbered starting at 1.

Example:

    If there were only three field values: "apple","banana","pear"
    then ord("apple")=1, ord("banana")=2, ord("pear")=3

WARNING: Ord depends on the position in an index and can thus change when other documents are inserted or deleted, or if a MultiSearcher is used.

WARNING: as of Solr 1.4, ord() and rord() can cause excess memory use since they must use a FieldCache entry at the top level reader, while sorting and function queries now use entries at the segment level. Hence sorting or using a different function query, in addition to ord()/rord() will double memory use.

PowSingleFunction

Function to raise the base "a" to the power "b"

NOTE: This was PowFloatFunction in Lucene

ProductSingleFunction

ProductSingleFunction returns the product of it's components.

NOTE: This was ProductFloatFunction in Lucene

QueryValueSource

QueryValueSource returns the relevance score of the query

RangeMapSingleFunction

RangeMapSingleFunction implements a map function over another ValueSource whose values fall within min and max inclusive to target.

Normally used as an argument to a FunctionQuery

NOTE: This was RangeMapFloatFunction in Lucene

ReciprocalSingleFunction

ReciprocalSingleFunction implements a reciprocal function f(x) = a/(mx+b), based on the value of a field or function as exported by ValueSource.

When a and b are equal, and x>=0, this function has a maximum value of 1 that drops as x increases. Increasing the value of a and b together results in a movement of the entire function to a flatter part of the curve.

These properties make this an idea function for boosting more recent documents.

Example: recip(ms(NOW,mydatefield),3.16e-11,1,1)

A multiplier of 3.16e-11 changes the units from milliseconds to years (since there are about 3.16e10 milliseconds per year). Thus, a very recent date will yield a value close to 1/(0+1) or 1, a date a year in the past will get a multiplier of about 1/(1+1) or 1/2, and date two years old will yield 1/(2+1) or 1/3.

NOTE: This was ReciprocalFloatFunction in Lucene

ReverseOrdFieldSource

Obtains the ordinal of the field value from the default Lucene FieldCache using and reverses the order.

The native lucene index order is used to assign an ordinal value for each field value.

Field values (terms) are lexicographically ordered by unicode value, and numbered starting at 1.

Example of reverse ordinal (rord):

    If there were only three field values: "apple","banana","pear"
    then rord("apple")=3, rord("banana")=2, ord("pear")=1

WARNING: Ord depends on the position in an index and can thus change when other documents are inserted or deleted, or if a MultiSearcher is used.

ScaleSingleFunction

Scales values to be between min and max.

This implementation currently traverses all of the source values to obtain their min and max.

This implementation currently cannot distinguish when documents have been deleted or documents that have no value, and 0.0 values will be used for these cases. This means that if values are normally all greater than 0.0, one can still end up with 0.0 as the min value to map from. In these cases, an appropriate map() function could be used as a workaround to change 0.0 to a value in the real range.

NOTE: This was ScaleFloatFunction in Lucene