Hi, The first example here ( https://cwiki.apache.org/confluence/display/MAHOUT/Recommender+Documentation) shows how to create a GenericUserBasedRecommender with a NearestNUserNeighborhood. My problem/question is that setting n to any small number seems to limit the coverage of the recommender, because the nearest n users are calculated without taking the target item into account. For example, given a user X and n = 10, if we want to estimatePreference() for an item Y, if this item is not rated by any user in the neighbourhood, the prediction will be NaN. I don't think that this is what one would expect from a user-based nearest-neighbour recommender, as Herlocker et al. (1999), who are cited in the example page above, didn't mention any change in coverage based on the number of nearest neighbours. Am I doing something wrong, or is this the way it should be? I have a feeling it is not the way it should be, because then using small neighbourhood sizes makes no sense as it severely restricts the ability of the recommender to estimate preferences.
Please note that I observed this behaviour in version 0.3, but it seems to be the same in the latest version. Cheers, Yanir
