org.apache.flink.api.java.sampling.RandomSampler 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
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* 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.flink.api.java.sampling;
import org.apache.flink.annotation.Internal;
import java.util.Iterator;
/**
* A data sample is a set of data selected from a statistical population by a defined procedure.
* RandomSampler helps to create data sample randomly.
*
* @param The type of sampler data.
*/
@Internal
public abstract class RandomSampler {
protected static final double EPSILON = 1e-5;
protected final Iterator emptyIterable = new SampledIterator() {
@Override
public boolean hasNext() {
return false;
}
@Override
public T next() {
return null;
}
};
/**
* Randomly sample the elements from input in sequence, and return the result iterator.
*
* @param input Source data
* @return The sample result.
*/
public abstract Iterator sample(Iterator input);
}
/**
* A simple abstract iterator which implements the remove method as unsupported operation.
*
* @param The type of iterator data.
*/
@Internal
abstract class SampledIterator implements Iterator {
@Override
public void remove() {
throw new UnsupportedOperationException("Do not support this operation.");
}
}