Pivot table style feature table interface

A pivot table is a cross-tabulation (or factorisation) of a table by a given column :

e.g. Pivot = Helix

Helix | other features observed
<none>| features observed where no helix feature exists
Score=1| features observed where helix feature with score==1 exists

This would present 'colour combinations' - i.e. allow the user to set intersection colours, and also allow the presentation of conditional distribution statistics such as feature frequencies/average scores/etc given the existence of a particular feature type/label combination.