## Package org.apache.lucene.facet.taxonomy

Taxonomy of Categories

See:
Description

Interface Summary
TaxonomyReader: TaxonomyReader is the read-only interface with which the faceted-search library uses the taxonomy during search time.
TaxonomyReader.ChildrenArrays: Equivalent representations of the taxonomy's parent info, used internally for efficient computation of facet results: "youngest child" and "oldest sibling"
TaxonomyWriter: TaxonomyWriter is the interface which the faceted-search library uses to dynamically build the taxonomy at indexing time.

Class Summary
CategoryPath: A CategoryPath holds a sequence of string components, specifying the hierarchical name of a category.

Exception Summary
InconsistentTaxonomyException: Exception indicating that a certain operation could not be performed on a taxonomy related object because of an inconsistency.

## Package org.apache.lucene.facet.taxonomy Description

# Taxonomy of Categories

Facets are defined using a hierarchy of categories, known as a Taxonomy
For example, in a book store application, a Taxonomy could have the following hierarchy:

- Author

- Mark Twain
- J. K. Rowling

- Date

- 2010
- 2009

The Taxonomy translates category-paths into category-ordinal and vice versa.