io.cdap.wrangler.sampling.Sampler Maven / Gradle / Ivy
/*
* Copyright © 2017-2019 Cask Data, 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.
*/
package io.cdap.wrangler.sampling;
import io.cdap.wrangler.api.annotations.PublicEvolving;
import java.util.Iterator;
/**
* This class is interface for implementing Sampler. It provides
* a set of data selected from a statistical population by the defined implementation.
*
* It helps create random samples of data easily.
*
* @param type of element to sample
*/
@PublicEvolving
public abstract class Sampler {
protected static final double EPSILON = 1e-5;
protected final Iterator emptyIterable = new SamplingIterator() {
@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 Scope data
* @return The sample result.
*/
public abstract Iterator sample(Iterator input);
}