Yes, the ChunkSample class is immutable and needs to encapsulate the
arrays.
If it would just hand out the array someone could modify it, but this
we do not want.
It its always good to have immutable classes, but yes it is slower
since we need
to make two copies just to ensure that. In the end I think we do not
loose much time here
during training. Immutable object are also thread safe which will be
important as soon as
we have multi-threaded training code.
These ArrayLists actually are quite nice if you have to do this
conversions, because they
bring very well tested methods for that. So that is why I used them.
Jörn
