hive中用java实现的udaf做线性回归

最新推荐文章于 2021-06-28 20:49:09 发布

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最新推荐文章于 2021-06-28 20:49:09 发布 · 2k 阅读

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本文介绍了如何在Hive中利用Java自定义UDAF（用户定义聚合函数）实现线性回归计算。通过示例展示了如何加载自定义jar包，并在SQL查询中应用该函数对数据进行分组计算。

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使用例子：

add jar some.jar;

create temporary function lr as'com.some.hive.LineRegressUdaf';

select lr(2+rand(),value+rand()) from testlog group by null;

[-7.134571349134458,0.006797483277215196]

java源码：

package com.some.hive;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.udf.generic.AbstractGenericUDAFResolver;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDAFEvaluator;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.StandardListObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.StandardStructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import com.some.hive.aggbuffer.LineAggregationBuffer;
import com.some.math.equation.EquationsSolver;
import com.some.math.equation.SingularSolver;
public class LineRegress extends AbstractGenericUDAFResolver {
	@Override
	public GenericUDAFEvaluator getEvaluator(TypeInfo[] arg0)
			throws SemanticException {
		return new Evaluator();
	}
    public static class Evaluator extends GenericUDAFEvaluator {
        private StandardStructObjectInspector structoi;
        private StandardListObjectInspector xxoi;
        private StandardListObjectInspector xyoi;
        private int n = 0;
        @Override
		public AggregationBuffer getNewAggregationBuffer() throws HiveException {