org.apache.hadoop.hive.ql.udf.UDFRand Maven / Gradle / Ivy
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* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.udf;
import java.util.Random;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.hive.ql.exec.vector.VectorizedExpressions;
import org.apache.hadoop.hive.ql.exec.vector.expressions.FuncRandNoSeed;
import org.apache.hadoop.hive.ql.exec.vector.expressions.FuncRand;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.io.LongWritable;
/**
* UDFRand.
*
*/
@Description(name = "rand",
value = "_FUNC_([seed]) - Returns a pseudorandom number between 0 and 1")
@UDFType(deterministic = false)
@VectorizedExpressions({FuncRandNoSeed.class, FuncRand.class})
public class UDFRand extends UDF {
private Random random;
private final DoubleWritable result = new DoubleWritable();
public UDFRand() {
}
public DoubleWritable evaluate() {
if (random == null) {
random = new Random();
}
result.set(random.nextDouble());
return result;
}
public DoubleWritable evaluate(LongWritable seed) {
if (random == null) {
long seedValue = 0;
if (seed != null) {
seedValue = seed.get();
}
random = new Random(seedValue);
}
result.set(random.nextDouble());
return result;
}
}