// you want to do that, you need to separate the categories into two
// category list (you'll still have one association list).
DirectoryTaxonomyReader taxo = new DirectoryTaxonomyReader(taxoDir);
// facet requests for two facets
FacetSearchParams fsp = new FacetSearchParams();
fsp.addFacetRequest(new AssociationIntSumFacetRequest(aint, 10));
fsp.addFacetRequest(new AssociationIntSumFacetRequest(bint, 10));
fsp.addFacetRequest(new AssociationFloatSumFacetRequest(afloat, 10));
fsp.addFacetRequest(new AssociationFloatSumFacetRequest(bfloat, 10));
Query q = new MatchAllDocsQuery();
FacetsCollector fc = new FacetsCollector(fsp, reader, taxo);