That looks like the best shortcut. It is one of the few places where the rows of one and the columns of the other are seen together. Now I know why you transpose the first input :-)
But, I have begun to wonder whether it is the right thing to do for a cross recommender because you are comparing a purchase vector to all view vectors--like comparing Honey Crisp to Cameo (couldn't resist an apples to apples joke). Co-occurrence makes sense but does cosine or log-likelihood? Maybe... On Apr 11, 2013, at 10:49 AM, Sebastian Schelter <s...@apache.org> wrote: > Do I have to create a SimilarityJob( matrixB, matrixA, similarityType ) to get this or have I missed something already in Mahout? It could be worth to investigate whether MatrixMultiplicationJob could be extended to compute similarities instead of dot products. Best, Sebastian
