weka.core.converters

Class AbstractLoader

java.lang.Object

weka.core.converters.AbstractLoader

All Implemented Interfaces:

Serializable, Loader, RevisionHandler

Direct Known Subclasses:

AbstractFileLoader, DatabaseLoader, TextDirectoryLoader

public abstract class AbstractLoader
extends Object
implements Loader

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

Version:

$Revision: 7454 $

Author:

Richard Kirkby ([email protected])

See Also:

Serialized Form

Field Summary

Fields inherited from interface weka.core.converters.Loader

BATCH, INCREMENTAL, NONE

Constructor Summary

Constructors

Constructor and Description
AbstractLoader()

Method Summary

Methods

Modifier and Type	Method and Description
abstract Instances	getDataSet() Return the full data set.
abstract Instance	getNextInstance(Instances structure) 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	reset() Default implementation sets retrieval mode to NONE
void	setRetrieval(int mode) Sets the retrieval mode.
void	setSource(File file) Default implementation throws an IOException.
void	setSource(InputStream input) Default implementation throws an IOException.

Methods inherited from class java.lang.Object

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

Methods inherited from interface weka.core.RevisionHandler

getRevision

Constructor Detail

AbstractLoader

public AbstractLoader()

Method Detail

setRetrieval

public void setRetrieval(int mode)

Sets the retrieval mode.

Specified by:

setRetrieval in interface Loader

Parameters:

mode - the retrieval mode

setSource

public void setSource(File file)
               throws IOException

Default implementation throws an IOException.

Specified by:

setSource in interface Loader

Parameters:

file - the File

Throws:

IOException - always

reset

public void reset()
           throws Exception

Default implementation sets retrieval mode to NONE

Specified by:

reset in interface Loader

Throws:

never.

Exception - if Loader can't be reset for some reason.

setSource

public void setSource(InputStream input)
               throws IOException

Default implementation throws an IOException.

Specified by:

setSource in interface Loader

Parameters:

input - the input stream

Throws:

IOException - always

getStructure

public abstract Instances getStructure()
                                throws 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:

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 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:

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(Instances structure)
                                  throws 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

Parameters:

structure - the dataset header information, will get updated in case of string or relational attributes

Returns:

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

Throws:

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).