This is a modified version of sofia-ml by D. Sculley. It differs from the original only in two additional parameters for sofia-kmeans RBF cluster mapping:
--cluster_mapping_threshold <float t>
After mapping, the values below the threshold will be set to zero (try t = 0.01 or 0.001). The resulting file might be smaller and sparsifying in this way may also help supervised learning (smaller error in classification or regression).
Make sure that t is small enough in relation to --cluster_mapping_param, because if all the features are smaller than the threshold, you'll just get a bunch of zeros.
--cluster_mapping_sparsity <int s>
Only use s nearest cluster centers for mapping. It is a stronger alternative to setting a threshold. The results with sparse mapping might be slightly worse, but the file certainly will be way smaller. Recommended for large data sets.
The modified files are:
sofia-ml/cluster-src/sf-cluster-centers.cc
sofia-ml/cluster-src/sf-cluster-centers.h
sofia-ml/src/sofia-kmeans.cc
See http://fastml.com/the-secret-of-the-big-guys/ for more.