oh well -- I guess we are hitting many nails we left out there to hurt outselves ;)

pretrain is indeed not used much, but in the classifiers to indeed just to get most of the common logic out, while allowing for easy customizations in derived classes... well -- haven't used that much

As for initialization -- if we would like to allow different initialization schemes, subclassing probably wouldn't be the best way.... why not just to allow taking "initialization_func" which would be provided the samples to spit out initial K to be assigned to _K?