/**
* 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,
* 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 org.apache.mahout.common.iterator;
import java.util.Iterator;
/**
* Wraps an {@link Iterable} whose {@link Iterable#iterator()} returns only some subset of the elements that
* it would, as determined by a iterator rate parameter.
*/
public final class SamplingIterable<T> implements Iterable<T> {
private final Iterable<? extends T> delegate;
private final double samplingRate;
public SamplingIterable(Iterable<? extends T> delegate, double samplingRate) {
this.delegate = delegate;
this.samplingRate = samplingRate;
}
@Override
public Iterator<T> iterator() {
return new SamplingIterator<T>(delegate.iterator(), samplingRate);
}
public static <T> Iterable<T> maybeWrapIterable(Iterable<T> delegate, double samplingRate) {
return samplingRate >= 1.0 ? delegate : new SamplingIterable<T>(delegate, samplingRate);
}
}