KFoldIterator (nd4j-api 1.0.0-beta4 API)

java.lang.Object
- org.nd4j.linalg.dataset.api.iterator.KFoldIterator

All Implemented Interfaces:

Serializable, Iterator<DataSet>, DataSetIterator
```
public class KFoldIterator
extends Object
implements DataSetIterator
```
Splits a dataset (represented as a single DataSet object) into k folds. DataSet is duplicated in memory once. Call .next() to get the k-1 folds to train on and then call .testfold() to get the corresponding kth fold for testing

Author:

Susan Eraly, Tamas Fenyvesi - modified KFoldIterator following the scikit-learn implementation (December 2018)

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected DataSet`	`allData`
`protected int[]`	`intervalBoundaries`
`protected int`	`k`
`protected int`	`kCursor`
`protected int`	`N`
`protected DataSetPreProcessor`	`preProcessor`
`protected DataSet`	`test`
`protected DataSet`	`train`

Constructor Summary

Constructors
Constructor and Description
`KFoldIterator(DataSet allData)` Create a k-fold cross-validation iterator given the dataset and k=10 train-test splits.
`KFoldIterator(int k, DataSet allData)` Create an iterator given the dataset with given k train-test splits N number of samples are split into k batches.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`asyncSupported()` 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.
`int`	`batch()` The number of examples in every fold is (N / k), except when (N % k) > 0, when the first (N % k) folds contain (N / k) + 1 examples
`List<String>`	`getLabels()` Get dataset iterator class labels, if any.
`DataSetPreProcessor`	`getPreProcessor()` Returns preprocessors, if defined
`boolean`	`hasNext()`
`int`	`inputColumns()` Input columns for the dataset
`DataSet`	`next()`
`DataSet`	`next(int num)` Like the standard next method but allows a customizable number of examples returned
`protected void`	`nextFold()`
`void`	`remove()`
`void`	`reset()` Shuffles the dataset and resets to the first fold
`boolean`	`resetSupported()` Is resetting supported by this DataSetIterator? Many DataSetIterators do support resetting, but some don't
`void`	`setPreProcessor(DataSetPreProcessor preProcessor)` Set a pre processor
`DataSet`	`testFold()`
`int`	`totalExamples()` Returns total number of examples in the dataset (all k folds)
`int`	`totalOutcomes()` The number of labels for the dataset

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Iterator
forEachRemaining

- Field Detail
  - allData
```
protected DataSet allData
```
  - k
```
protected int k
```
  - N
```
protected int N
```
  - intervalBoundaries
```
protected int[] intervalBoundaries
```
  - kCursor
```
protected int kCursor
```
  - test
```
protected DataSet test
```
  - train
```
protected DataSet train
```
  - preProcessor
```
protected DataSetPreProcessor preProcessor
```
- Constructor Detail
  - KFoldIterator
```
public KFoldIterator(DataSet allData)
```
    Create a k-fold cross-validation iterator given the dataset and k=10 train-test splits. N number of samples are split into k batches. The first (N%k) batches contain (N/k)+1 samples, while the remaining batches contain (N/k) samples. In case the number of samples (N) in the dataset is a multiple of k, all batches will contain (N/k) samples.
    
    Parameters:
    
    allData - DataSet to split into k folds
  - KFoldIterator
```
public KFoldIterator(int k,
                     DataSet allData)
```
    Create an iterator given the dataset with given k train-test splits N number of samples are split into k batches. The first (N%k) batches contain (N/k)+1 samples, while the remaining batches contain (N/k) samples. In case the number of samples (N) in the dataset is a multiple of k, all batches will contain (N/k) samples.
    
    Parameters:
    
    k - number of folds (optional, defaults to 10)
    
    allData - DataSet to split into k folds
- Method Detail
  - next
```
public DataSet next(int num)
             throws UnsupportedOperationException
```
    Description copied from interface: DataSetIterator
    
    Like the standard next method but allows a customizable number of examples returned
    
    Specified by:
    
    next in interface DataSetIterator
    
    Parameters:
    
    num - the number of examples
    
    Returns:
    
    the next data applyTransformToDestination
    
    Throws:
    
    UnsupportedOperationException
  - totalExamples
```
public int totalExamples()
```
    Returns total number of examples in the dataset (all k folds)
    
    Returns:
    
    total number of examples in the dataset including all k folds
  - inputColumns
```
public int inputColumns()
```
    Description copied from interface: DataSetIterator
    
    Input columns for the dataset
    
    Specified by:
    
    inputColumns in interface DataSetIterator
    
    Returns:
  - totalOutcomes
```
public int totalOutcomes()
```
    Description copied from interface: DataSetIterator
    
    The number of labels for the dataset
    
    Specified by:
    
    totalOutcomes in interface DataSetIterator
    
    Returns:
  - resetSupported
```
public boolean resetSupported()
```
    Description copied from interface: DataSetIterator
    
    Is resetting supported by this DataSetIterator? Many DataSetIterators do support resetting, but some don't
    
    Specified by:
    
    resetSupported in interface DataSetIterator
    
    Returns:
    
    true if reset method is supported; false otherwise
  - asyncSupported
```
public boolean asyncSupported()
```
    Description copied from interface: DataSetIterator
    
    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
    
    Specified by:
    
    asyncSupported in interface DataSetIterator
    
    Returns:
    
    true if asynchronous prefetching from this iterator is OK; false if asynchronous prefetching should not be used with this iterator
  - reset
```
public void reset()
```
    Shuffles the dataset and resets to the first fold
    
    Specified by:
    
    reset in interface DataSetIterator
  - batch
```
public int batch()
```
    The number of examples in every fold is (N / k), except when (N % k) > 0, when the first (N % k) folds contain (N / k) + 1 examples
    
    Specified by:
    
    batch in interface DataSetIterator
    
    Returns:
    
    examples in a fold
  - setPreProcessor
```
public void setPreProcessor(DataSetPreProcessor preProcessor)
```
    Description copied from interface: DataSetIterator
    
    Set a pre processor
    
    Specified by:
    
    setPreProcessor in interface DataSetIterator
    
    Parameters:
    
    preProcessor - a pre processor to set
  - getPreProcessor
```
public DataSetPreProcessor getPreProcessor()
```
    Description copied from interface: DataSetIterator
    
    Returns preprocessors, if defined
    
    Specified by:
    
    getPreProcessor in interface DataSetIterator
    
    Returns:
  - getLabels
```
public List<String> getLabels()
```
    Description copied from interface: DataSetIterator
    
    Get dataset iterator class labels, if any. Note that implementations are not required to implement this, and can simply return null
    
    Specified by:
    
    getLabels in interface DataSetIterator
  - hasNext
```
public boolean hasNext()
```
    Specified by:
    
    hasNext in interface Iterator<DataSet>
  - next
```
public DataSet next()
```
    Specified by:
    
    next in interface Iterator<DataSet>
  - remove
```
public void remove()
```
    Specified by:
    
    remove in interface Iterator<DataSet>
  - nextFold
```
protected void nextFold()
```
  - testFold
```
public DataSet testFold()
```
    Returns:
    
    the held out fold as a dataset

Class KFoldIterator

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Iterator

Field Detail

allData

k

N

intervalBoundaries

kCursor

test

train

preProcessor

Constructor Detail

KFoldIterator

KFoldIterator

Method Detail

next

totalExamples

inputColumns

totalOutcomes

resetSupported

asyncSupported

reset

batch

setPreProcessor

getPreProcessor

getLabels

hasNext

next

remove

nextFold

testFold