SumArrayUDF.java

package brickhouse.udf.timeseries;
/**
 * Copyright 2012 Klout, Inc
 *
 * Licensed 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.
 *
 **/


import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ListObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.log4j.Logger;

import java.util.List;

/**
 * Hive UDF to sum the elements of an array
 */
@Description(
        name = "sum_array",
        value = " sum an array of doubles"
)
public class SumArrayUDF extends GenericUDF {
    private static final Logger LOG = Logger.getLogger(SumArrayUDF.class);
    private ListObjectInspector listInspector;


    public Double evaluate(List<Object> strArray) {
        double total = 0.0;
        for (Object obj : strArray) {

            Object dblObj = ((PrimitiveObjectInspector) (listInspector.getListElementObjectInspector())).getPrimitiveJavaObject(obj);
            if (dblObj instanceof Number) {
                Number dblNum = (Number) dblObj;
                total += dblNum.doubleValue();
            } else {
                //// Try to coerce it otherwise
                String dblStr = (dblObj.toString());
                try {
                    Double dblCoerce = Double.parseDouble(dblStr);
                    total += dblCoerce;
                } catch (NumberFormatException formatExc) {
                    LOG.info(" Unable to interpret " + dblStr + " as a number");
                }
            }

        }
        return total;
    }

    @Override
    public Object evaluate(DeferredObject[] arg0) throws HiveException {
        List argList = listInspector.getList(arg0[0].get());
        if (argList != null)
            return evaluate(argList);
        else
            return null;
    }

    @Override
    public String getDisplayString(String[] arg0) {
        return "sum_array()";
    }

    @Override
    public ObjectInspector initialize(ObjectInspector[] arg0)
            throws UDFArgumentException {
        this.listInspector = (ListObjectInspector) arg0[0];
        LOG.info(" Sum Array input type is " + listInspector + " element = " + listInspector.getListElementObjectInspector());

        ObjectInspector returnType = PrimitiveObjectInspectorFactory.javaDoubleObjectInspector;
        return returnType;
    }
}