org.apache.pig.builtin.COV Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of pig Show documentation
There is a newer version: 0.17.0
/*
 * 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 java.util.Iterator;
import java.util.Vector;

import org.apache.pig.Algebraic;
import org.apache.pig.EvalFunc;
import org.apache.pig.data.DataBag;
import org.apache.pig.data.DataType;
import org.apache.pig.data.DefaultBagFactory;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.logicalLayer.schema.Schema;

/**
* Computes the covariance between sets of data.  The returned value 
* will be a bag which will contain a tuple for each combination of input 
* schema and inside tuple we will have two schema name and covariance between 
* those  two schemas. 
* 
* A = load 'input.xml' using PigStorage(':');

* B = group A all;

* D = foreach B generate group,COV(A.$0,A.$1,A.$2);

*/
public class COV extends EvalFunc implements Algebraic {
    //name of the schemas. Initialize when user use define
    protected VectorschemaName = new Vector();
    //flag to indicate if define is called or not. 
    private boolean flag = false;
    
    public COV(){}
    
    
    public COV(String... schemaName){
        for(int i=0;i {
        @Override
        public Tuple exec(Tuple input) throws IOException {
            if (input == null || input.size() == 0)
                return null;

            Tuple output = TupleFactory.getInstance().newTuple();
            try {
                for(int i=0;i {
        
        @Override
        public Tuple exec(Tuple input) throws IOException {
            try{
                return combine((DataBag)input.get(0));
            }catch(Exception e){
                throw new IOException("Caught exception in COV.Intermed", e);
            }
        }
    }

    public static class Final extends EvalFunc {
        protected VectorschemaName = new Vector();
        boolean flag = false;
        
        public Final(){}
        
        public Final(String... schemaName){
            for(int i=0;i it = values.iterator(); it.hasNext();ct++) {
            Tuple t = it.next();
            try{ tuple.set(ct, t);}catch(Exception e){}
        }
        
        try{
            Tuple temp = (Tuple)tuple.get(0);
            int size = temp.size();
            for(int i=0;i iterator_x = first.iterator();
        Iterator iterator_y = second.iterator();
        try{
            while(iterator_x.hasNext()){
                double x = (Double)iterator_x.next().get(0);
                double y = (Double)iterator_y.next().get(0);
                sum_x_y+=x*y;
                sum_x+=x;
                sum_y+=y;
            }
        }catch (Exception e){
            throw new IOException("Caught exception processing input", e);
        }
        
        Tuple result = TupleFactory.getInstance().newTuple(3);
        try{
            result.set(0, sum_x_y);
            result.set(1, sum_x);
            result.set(2, sum_y);
        }catch(Exception e) {
            throw new IOException("Caught exception processing result", e);
        }
        return result;
        
    }
    
    @Override
    public Schema outputSchema(Schema input) {
        return new Schema(new Schema.FieldSchema(getSchemaName(this.getClass().getName().toLowerCase(), input), DataType.BAG));
    }

}