14. The computing device of claim 13 wherein the cluster index data structure for a feature stores, for each object in the collection, a hash code representing that feature for that object, and wherein objects are clustered that are feature similar using the hash code to represent the feature of an object.
14. The computing device of claim 13 wherein the cluster index data structure for a feature stores, for each object in the collection, a hash code representing that feature for that object, and wherein objects are clustered that are feature similar using the hash code to represent the feature of an object. 15. The computing device of claim 14 wherein feature similarity for a feature is based on a Hamming distance between hash codes of that feature.