Pig TOBAG

gistfile1.txt

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.pig.builtin;


import java.io.IOException;

import org.apache.pig.EvalFunc;
import org.apache.pig.data.BagFactory;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;

/**
 * This class takes a list of items and puts them into a bag
 * T = foreach U generate TOBAG($0, $1, $2);
 * It's like saying this:
 * T = foreach U generate {($0), ($1), ($2)}
 */
public class TOBAG extends EvalFunc<DataBag> {

    @Override
    public DataBag exec(Tuple input) throws IOException {
        try {
            DataBag bag = BagFactory.getInstance().newDefaultBag();

            for (int i = 0; i < input.size(); ++i) {
                final Object object = input.get(i);
                if (object != null) {
                    Tuple tp2 = TupleFactory.getInstance().newTuple(1);
                    tp2.set(0, object);
                    bag.add(tp2);
                }
            }

            return bag;
        } catch (Exception ee) {
            throw new RuntimeException("Error while creating a bag", ee);
        }
    }
}