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

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

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

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

Constructor Detail

AbstractLoader

public AbstractLoader()

Method Detail

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);
    |}