2013/6/17 Mathieu Blondel <[email protected]>: > On Mon, Jun 17, 2013 at 10:27 PM, Lars Buitinck <[email protected]> wrote: >> >> In pairwise L2R, loss functions are defined on pairs of samples, but >> only for those pairs that pertain to the same query (since ranking is >> done per query). So, you need the query information with the samples. > > Actually, if I am not mistaken, the query grouping is not a requirement but > just an heuristic to speed up training. > Technically, samples that do not belong to the same query should be ranked > lower than those that do. However, considering all possible pairs would be > computationally > too expensive. Therefore, learning algorithms typically only enforce that > samples within the same > query group are properly ranked.
But then you'd need the query id for both samples to compute the loss function :) -- Lars Buitinck Scientific programmer, ILPS University of Amsterdam ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Scikit-learn-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/scikit-learn-general
