[Java-ML-support] instance key, how to set?

[טל ד. <tal...@gm...>]

It isn't clear from the documentation how to set a key for an instance
(row) in a dataset.
Sometimes, one has to find a sparseInstance, by key, in order to add values
to it, but it isn't clear how to accomplish this.

Also, the word class in the documentation is confusing, and I think should
be changed to classification.

I tried to figure out how to use filters but didn't get it from the
javadocs.

Any tutotial out there? can someone help me understand if Java-ML instances
can be used with key, and then values of instance? the getID seems to
through a random number.

As a last resort, I can create a HashMap that maps each userID, for an
instance row number in the dataset, but I want to know if JAva-ML already
supports that simple action.

Thanks,
Tal