Package org.apache.lucene.facet.taxonomy

Taxonomy of Categories

Facets are defined using a hierarchy of categories, known as a Taxonomy. For example, the taxonomy of a book store application might have the following structure:

• Author
  • Mark Twain
  • J. K. Rowling

• Date
  • 2010
    • March
    • April
  • 2009

The Taxonomy translates category-paths into interger identifiers (often termed ordinals) and vice versa. The category Author/Mark Twain adds two nodes to the taxonomy: Author and Author/Mark Twain, each is assigned a different ordinal. The taxonomy maintains the invariant that a node always has an ordinal that is < all its children.

Interface Summary

Interface	Description
TaxonomyWriter	TaxonomyWriter is the interface which the faceted-search library uses to dynamically build the taxonomy at indexing time.

Class Summary

Class	Description
AssociationFacetField	Add an instance of this to your Document to add a facet label associated with an arbitrary byte[].
CachedOrdinalsReader	A per-segment cache of documents' facet ordinals.
CachedOrdinalsReader.CachedOrds	Holds the cached ordinals in two paralel int[] arrays.
CategoryPath	Holds a sequence of string components, specifying the hierarchical name of a category.
DocValuesOrdinalsReader	Decodes ordinals previously indexed into a BinaryDocValues field
FacetLabel	Holds a sequence of string components, specifying the hierarchical name of a category.
FastTaxonomyFacetCounts	Computes facets counts, assuming the default encoding into DocValues was used.
FloatAssociationFacetField	Add an instance of this to your Document to add a facet label associated with a float.
FloatTaxonomyFacets	Base class for all taxonomy-based facets that aggregate to a per-ords float[].
IntAssociationFacetField	Add an instance of this to your Document to add a facet label associated with an int.
IntTaxonomyFacets	Base class for all taxonomy-based facets that aggregate to a per-ords int[].
LRUHashMap<K,V>	LRUHashMap is an extension of Java's HashMap, which has a bounded size(); When it reaches that size, each time a new element is added, the least recently used (LRU) entry is removed.
OrdinalsReader	Provides per-document ordinals.
OrdinalsReader.OrdinalsSegmentReader	Returns ordinals for documents in one segment.
ParallelTaxonomyArrays	Returns 3 arrays for traversing the taxonomy: parents: parents[i] denotes the parent of category ordinal i. children: children[i] denotes a child of category ordinal i. siblings: siblings[i] denotes the sibling of category ordinal i. To traverse the taxonomy tree, you typically start with children[0] (ordinal 0 is reserved for ROOT), and then depends if you want to do DFS or BFS, you call children[children[0]] or siblings[children[0]] and so forth, respectively.
PrintTaxonomyStats	Prints how many ords are under each dimension.
SearcherTaxonomyManager	Manages near-real-time reopen of both an IndexSearcher and a TaxonomyReader.
SearcherTaxonomyManager.SearcherAndTaxonomy	Holds a matched pair of IndexSearcher and TaxonomyReader
TaxonomyFacetCounts	Reads from any OrdinalsReader; use FastTaxonomyFacetCounts if you are using the default encoding from BinaryDocValues.
TaxonomyFacets	Base class for all taxonomy-based facets impls.
TaxonomyFacetSumFloatAssociations	Aggregates sum of int values previously indexed with FloatAssociationFacetField, assuming the default encoding.
TaxonomyFacetSumIntAssociations	Aggregates sum of int values previously indexed with IntAssociationFacetField, assuming the default encoding.
TaxonomyFacetSumValueSource	Aggregates sum of values from FunctionValues.doubleVal(int), for each facet label.
TaxonomyFacetSumValueSource.ScoreValueSource	ValueSource that returns the score for each hit; use this to aggregate the sum of all hit scores for each facet label.
TaxonomyReader	TaxonomyReader is the read-only interface with which the faceted-search library uses the taxonomy during search time.
TaxonomyReader.ChildrenIterator	An iterator over a category's children.