question: protected List < ITEM_TYPE > selectFoldTrainItems ( List < ITEM_TYPE > items , int nFolds , int fold ) { List < ITEM_TYPE > trainItems = new ArrayList < ITEM_TYPE > ( ) ; for ( int i = 0 ; i < items . size ( ) ; ++ i ) { if ( i % nFolds != fold ) { trainItems . add ( items . get ( i ) ) ; } } return trainItems ; }
target:  Determines which items should be used for training in one fold of a cross-validation. The default implementation includes all items except for every (nFolds)th item, but this may be overridden in subclasses.