org.nd4j.linalg.dataset.api.iterator.DataSetIterator Maven / Gradle / Ivy
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* Copyright (c) 2015-2018 Skymind, Inc.
*
* This program and the accompanying materials are made available under the
* terms of the Apache License, Version 2.0 which is available at
* https://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.
*
* SPDX-License-Identifier: Apache-2.0
******************************************************************************/
package org.nd4j.linalg.dataset.api.iterator;
import org.nd4j.linalg.dataset.DataSet;
import org.nd4j.linalg.dataset.api.DataSetPreProcessor;
import java.io.Serializable;
import java.util.Iterator;
import java.util.List;
/**
* A DataSetIterator handles
* traversing through a dataset and preparing
*
* data for a neural network.
*
* Typical usage of an iterator is akin to:
*
* DataSetIterator iter = ..;
*
* while(iter.hasNext()) {
* DataSet d = iter.next();
* //iterate network...
* }
*
*
* For custom numbers of examples/batch sizes you can call:
*
* iter.next(num)
*
* where num is the number of examples to fetch
*
* @author Adam Gibson
*/
public interface DataSetIterator extends Iterator, Serializable {
/**
* Like the standard next method but allows a
* customizable number of examples returned
*
* @param num the number of examples
* @return the next data applyTransformToDestination
*/
DataSet next(int num);
/**
* Input columns for the dataset
*
* @return
*/
int inputColumns();
/**
* The number of labels for the dataset
*
* @return
*/
int totalOutcomes();
/**
* Is resetting supported by this DataSetIterator? Many DataSetIterators do support resetting,
* but some don't
*
* @return true if reset method is supported; false otherwise
*/
boolean resetSupported();
/**
* Does this DataSetIterator support asynchronous prefetching of multiple DataSet objects?
* Most DataSetIterators do, but in some cases it may not make sense to wrap this iterator in an
* iterator that does asynchronous prefetching. For example, it would not make sense to use asynchronous
* prefetching for the following types of iterators:
* (a) Iterators that store their full contents in memory already
* (b) Iterators that re-use features/labels arrays (as future next() calls will overwrite past contents)
* (c) Iterators that already implement some level of asynchronous prefetching
* (d) Iterators that may return different data depending on when the next() method is called
*
* @return true if asynchronous prefetching from this iterator is OK; false if asynchronous prefetching should not
* be used with this iterator
*/
boolean asyncSupported();
/**
* Resets the iterator back to the beginning
*/
void reset();
/**
* Batch size
*
* @return
*/
int batch();
/**
* Set a pre processor
*
* @param preProcessor a pre processor to set
*/
void setPreProcessor(DataSetPreProcessor preProcessor);
/**
* Returns preprocessors, if defined
*
* @return
*/
DataSetPreProcessor getPreProcessor();
/**
* Get dataset iterator class labels, if any.
* Note that implementations are not required to implement this, and can simply return null
*/
List getLabels();
}