weka.core.converters
Class AbstractLoader

java.lang.Object
  weka.core.converters.AbstractLoader

All Implemented Interfaces:

Loader, java.io.Serializable

Direct Known Subclasses:

ArffLoader, C45Loader, CSVLoader, SerializedInstancesLoader, TreeLoader

public abstract class AbstractLoader

extends java.lang.Object

implements Loader

Abstract class gives default implementation of setSource methods. All other methods must be overridden.

Version:

$Revision: 1.6 $

Author:

Richard Kirkby (rkirkby@cs.waikato.ac.nz)

See Also:

Serialized Form

Field Summary

protected static int	BATCH
protected static int	INCREMENTAL
protected int	m_retrieval The current retrieval mode
protected static int	NONE The retrieval modes

Constructor Summary

AbstractLoader()

Method Summary

abstract Instances	getDataSet() Return the full data set.
abstract Instance	getNextInstance() Read the data set incrementally---get the next instance in the data set or returns null if there are no more instances to get.
protected int	getRetrieval() Gets the retrieval mode.
abstract Instances	getStructure() Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
protected void	setRetrieval(int mode) Sets the retrieval mode.
void	setSource(java.io.File file) Default implementation throws an IOException.
void	setSource(java.io.InputStream input) Default implementation throws an IOException.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NONE

protected static final int NONE

The retrieval modes

See Also:

Constant Field Values

BATCH

protected static final int BATCH

See Also:

Constant Field Values

INCREMENTAL

protected static final int INCREMENTAL

See Also:

Constant Field Values

m_retrieval

protected int m_retrieval

The current retrieval mode

Constructor Detail

AbstractLoader

public AbstractLoader()

Method Detail

setRetrieval

protected void setRetrieval(int mode)

Sets the retrieval mode.

Parameters:

mode - the retrieval mode

getRetrieval

protected int getRetrieval()

Gets the retrieval mode.

Returns:

the retrieval mode

setSource

public void setSource(java.io.File file)
               throws java.io.IOException

Default implementation throws an IOException.

Specified by:

setSource in interface Loader

Parameters:

file - the File

Throws:

java.io.IOException - always

setSource

public void setSource(java.io.InputStream input)
               throws java.io.IOException

Default implementation throws an IOException.

Specified by:

setSource in interface Loader

Parameters:

input - the input stream

Throws:

java.io.IOException - always

getStructure

public abstract Instances getStructure()
                                throws java.io.IOException

Description copied from interface: Loader

Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.

Specified by:

getStructure in interface Loader

Returns:

the structure of the data set as an empty set of Instances

Throws:

java.io.IOException - if there is no source or parsing fails

    public_normal_behavior
      requires: model_sourceSupplied == true
                && model_structureDetermined == false
                && (* successful parse *);
      modifiable: model_structureDetermined;
      ensures: \result != null
               && \result.numInstances() == 0
               && model_structureDetermined == true;
  also
    public_exceptional_behavior
      requires: model_sourceSupplied == false
                || (* unsuccessful parse *);
      signals: (IOException);
 

getDataSet

public abstract Instances getDataSet()
                              throws java.io.IOException

Description copied from interface: Loader

Return the full data set. If the structure hasn't yet been determined by a call to getStructure then the method should do so before processing the rest of the data set.

Specified by:

getDataSet in interface Loader

Returns:

the full data set as an Instances object

Throws:

java.io.IOException - if there is an error during parsing or if getNextInstance has been called on this source (either incremental or batch loading can be used, not both).

    public_normal_behavior
      requires: model_sourceSupplied == true
                && (* successful parse *);
      modifiable: model_structureDetermined;
      ensures: \result != null
               && \result.numInstances() >= 0
               && model_structureDetermined == true;
  also
    public_exceptional_behavior
      requires: model_sourceSupplied == false
                || (* unsuccessful parse *);
      signals: (IOException);
 

getNextInstance

public abstract Instance getNextInstance()
                                  throws java.io.IOException

Description copied from interface: Loader

Read the data set incrementally---get the next instance in the data set or returns null if there are no more instances to get. If the structure hasn't yet been determined by a call to getStructure then method should do so before returning the next instance in the data set. If it is not possible to read the data set incrementally (ie. in cases where the data set structure cannot be fully established before all instances have been seen) then an exception should be thrown.

Specified by:

getNextInstance in interface Loader

Returns:

the next instance in the data set as an Instance object or null if there are no more instances to be read

Throws:

java.io.IOException - if there is an error during parsing or if getDataSet has been called on this source (either incremental or batch loading can be used, not both).

    public_normal_behavior
    {|
       requires: model_sourceSupplied == true
                 && (* successful parse *);
       modifiable: model_structureDetermined;
       ensures: model_structureDetermined == true
                && \result != null;
     also
       requires: model_sourceSupplied == true
                 && (* no further input *);
       modifiable: model_structureDetermined;
       ensures: model_structureDetermined == true
                && \result == null;
    |}
  also
    public_exceptional_behavior
    {|
       requires: model_sourceSupplied == false
                 || (* unsuccessful parse *);
       signals: (IOException);
     also
       requires: (* unable to process data set incrementally *);
       signals: (IOException);
    |}