Type: New Feature
Affects Version/s: None
Fix Version/s: 8.2
The current facet expression is a generic tool for creating multi-dimension aggregations. The facet2D Streaming Expression has semantics specific for 2 dimensional facets which are designed to be pivoted into a matrix and operated on by Math Expressions.
facet2D will use the json facet API under the covers.
The example above will return tuples containing the top 300 diseases and the top ten symptoms for each disease.
Using math expression the tuples can be pivoted into a matrix where the rows of the matrix are the diseases, the columns of the matrix are the symptoms and the cells in the matrix contain the counts. This matrix can then be clustered to find clusters of diseases that are correlated by symptoms.
The implementation plan for this ticket is to create a new stream called Facet2DStream. The FacetStream code is a good starting point for the new implementation and can be adapted for the Facet2D parameters. Similar tests to the FacetStream can be added to StreamExpressionTest