public List<NumericColumn<?>> numericColumns(int... columnIndices) {
        List<NumericColumn<?>> cols = new ArrayList<>();
        for (int i : columnIndices) {
            cols.add(numberColumn(i));
        }

        return cols;
    }
public List < NumericColumn < ? > > numericColumns ( int ... columnIndices ) { List < NumericColumn < ? > > cols = new ArrayList < > ( ) ; for ( int i : columnIndices ) { cols . add ( numberColumn ( i ) ) ; } return cols ; }
Returns all the NumericColumns in the relation