Package org.apache.lucene.facet.taxonomy

Taxonomy of Categories

See:
Description

Interface Summary

TaxonomyWriter

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

Class Summary

CategoryPath	Holds a sequence of string components, specifying the hierarchical name of a category.
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.
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.

Package org.apache.lucene.facet.taxonomy Description

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.