weka.core.converters

Interface Loader

All Superinterfaces:

RevisionHandler, java.io.Serializable

All Known Implementing Classes:

AbstractFileLoader, AbstractLoader, ArffLoader, C45Loader, CSVLoader, DatabaseLoader, LibSVMLoader, SerializedInstancesLoader, SVMLightLoader, TextDirectoryLoader, XRFFLoader

public interface Loader
extends java.io.Serializable, RevisionHandler

Interface to something that can load Instances from an input source in some format.

Version:

$Revision: 7454 $

Author:

Mark Hall (mhall@cs.waikato.ac.nz)

Field Summary

Fields

Modifier and Type	Field and Description
static int	BATCH
static int	INCREMENTAL
static int	NONE The retrieval modes

Method Summary

Modifier and Type	Method and Description
Instances	getDataSet() Return the full data set.
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.
Instances	getStructure() Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
void	reset() Resets the Loader object ready to begin loading.
void	setRetrieval(int mode) Sets the retrieval mode.
void	setSource(java.io.File file) Resets the Loader object and sets the source of the data set to be the supplied File object.
void	setSource(java.io.InputStream input) Resets the Loader object and sets the source of the data set to be the supplied InputStream.

Methods inherited from interface weka.core.RevisionHandler

getRevision

Field Detail

NONE

static final int NONE

The retrieval modes

See Also:

Constant Field Values

BATCH

static final int BATCH

See Also:

Constant Field Values

INCREMENTAL

static final int INCREMENTAL

See Also:

Constant Field Values

Method Detail

setRetrieval

void setRetrieval(int mode)

Sets the retrieval mode. Note: Some loaders may not be able to implement incremental loading.

Parameters:

mode - the retrieval mode

reset

void reset()
    throws java.lang.Exception

Resets the Loader object ready to begin loading. If there is an existing source, implementations should attempt to reset in such a fashion as to be able to load from the beginning of the source.

Throws:

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

setSource

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

Resets the Loader object and sets the source of the data set to be the supplied File object.

Parameters:

file - the File

Throws:

java.io.IOException - if an error occurs support loading from a File.

    public_normal_behavior
      requires: file != null
                && (* file exists *);
      modifiable: model_sourceSupplied, model_structureDetermined;
      ensures: model_sourceSupplied == true 
               && model_structureDetermined == false;
  also
    public_exceptional_behavior
      requires: file == null
                || (* file does not exist *);
    signals: (IOException);
 

setSource

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

Resets the Loader object and sets the source of the data set to be the supplied InputStream.

Parameters:

input - the source InputStream

Throws:

java.io.IOException - if this Loader doesn't support loading from a File.

getStructure

Instances getStructure()
                throws java.io.IOException

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

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

Instances getDataSet()
              throws java.io.IOException

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.

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

Instance getNextInstance(Instances structure)
                  throws java.io.IOException

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.

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:

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).