DataSetOp op = getCurrentOp();
if (op == null || !(op instanceof DataSetGroup)) {
dataSetLookup.addOperation(new DataSetGroup());
}
DataSetGroup gOp = (DataSetGroup) getCurrentOp();
gOp.addGroupFunction(new GroupFunction(columnId, newColumnId, function));
return (T) this;
}
public T select(String... intervalNames) {
DataSetOp op = getCurrentOp();