* @param indexes as numbered in {@link columns}, not {@link expandedColumns}
* @return the result's {@link expandedColumns} are the projected-on columns
*/
public Relation project(int[] indexes) {
ColumnIndexesImpl c = new ColumnIndexesImpl(this.columns());
c = c.select(indexes);
return makeNew(Terms.project(this.formula(), indexes), c, c);
}
private Relation project(Iterable<Integer> projectionInts) {
return project(Ints.toArray(Lists.newArrayList(projectionInts)));