weka.core.converters

Class ConverterUtils.DataSource

java.lang.Object

weka.core.converters.ConverterUtils.DataSource

All Implemented Interfaces:

java.io.Serializable, RevisionHandler

Enclosing class:

ConverterUtils

public static class ConverterUtils.DataSource
extends java.lang.Object
implements java.io.Serializable, RevisionHandler

Helper class for loading data from files and URLs. Via the ConverterUtils class it determines which converter to use for loading the data into memory. If the chosen converter is an incremental one, then the data will be loaded incrementally, otherwise as batch. In both cases the same interface will be used (hasMoreElements, nextElement). Before the data can be read again, one has to call the reset method. The data source can also be initialized with an Instances object, in order to provide a unified interface to files and already loaded datasets.

Version:

$Revision: 6416 $

Author:

FracPete (fracpete at waikato dot ac dot nz)

See Also:

hasMoreElements(Instances), nextElement(Instances), reset(), ConverterUtils.DataSink, Serialized Form

Constructor Summary

Constructors

Constructor and Description
DataSource(java.io.InputStream stream) Initializes the datasource with the given input stream.
DataSource(Instances inst) Initializes the datasource with the given dataset.
DataSource(Loader loader) Initializes the datasource with the given Loader.
DataSource(java.lang.String location) Tries to load the data from the file.

Method Summary

Modifier and Type	Method and Description
Instances	getDataSet() returns the full dataset, can be null in case of an error.
Instances	getDataSet(int classIndex) returns the full dataset with the specified class index set, can be null in case of an error.
Loader	getLoader() returns the determined loader, null if the DataSource was initialized with data alone and not a file/URL.
java.lang.String	getRevision() Returns the revision string.
Instances	getStructure() returns the structure of the data.
Instances	getStructure(int classIndex) returns the structure of the data, with the defined class index.
boolean	hasMoreElements(Instances structure) returns whether there are more Instance objects in the data.
static boolean	isArff(java.lang.String location) returns whether the extension of the location is likely to be of ARFF format, i.e., ending in ".arff" or ".arff.gz" (case-insensitive).
boolean	isIncremental() returns whether the loader is an incremental one.
static void	main(java.lang.String[] args) for testing only - takes a data file as input.
Instance	nextElement(Instances dataset) returns the next element and sets the specified dataset, null if none available.
static Instances	read(java.io.InputStream stream) convencience method for loading a dataset in batch mode from a stream.
static Instances	read(Loader loader) convencience method for loading a dataset in batch mode.
static Instances	read(java.lang.String location) convencience method for loading a dataset in batch mode.
void	reset() resets the loader.

Methods inherited from class java.lang.Object

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

Constructor Detail

DataSource

public DataSource(java.lang.String location)
           throws java.lang.Exception

Tries to load the data from the file. Can be either a regular file or a web location (http://, https://, ftp:// or file://).

Parameters:

location - the name of the file to load

Throws:

java.lang.Exception - if initialization fails

DataSource

public DataSource(Instances inst)

Initializes the datasource with the given dataset.

Parameters:

inst - the dataset to use

DataSource

public DataSource(Loader loader)

Initializes the datasource with the given Loader.

Parameters:

loader - the Loader to use

DataSource

public DataSource(java.io.InputStream stream)

Initializes the datasource with the given input stream. This stream is always interpreted as ARFF.

Parameters:

stream - the stream to use

Method Detail

isArff

public static boolean isArff(java.lang.String location)

returns whether the extension of the location is likely to be of ARFF format, i.e., ending in ".arff" or ".arff.gz" (case-insensitive).

Parameters:

location - the file location to check

Returns:

true if the location seems to be of ARFF format

isIncremental

public boolean isIncremental()

returns whether the loader is an incremental one.

Returns:

true if the loader is a true incremental one

getLoader

public Loader getLoader()

returns the determined loader, null if the DataSource was initialized with data alone and not a file/URL.

Returns:

the loader used for retrieving the data

getDataSet

public Instances getDataSet()
                     throws java.lang.Exception

returns the full dataset, can be null in case of an error.

Returns:

the full dataset

Throws:

java.lang.Exception - if resetting of loader fails

getDataSet

public Instances getDataSet(int classIndex)
                     throws java.lang.Exception

returns the full dataset with the specified class index set, can be null in case of an error.

Parameters:

classIndex - the class index for the dataset

Returns:

the full dataset

Throws:

java.lang.Exception - if resetting of loader fails

reset

public void reset()
           throws java.lang.Exception

resets the loader.

Throws:

java.lang.Exception - if resetting fails

getStructure

public Instances getStructure()
                       throws java.lang.Exception

returns the structure of the data.

Returns:

the structure of the data

Throws:

java.lang.Exception - if something goes wrong

getStructure

public Instances getStructure(int classIndex)
                       throws java.lang.Exception

returns the structure of the data, with the defined class index.

Parameters:

classIndex - the class index for the dataset

Returns:

the structure of the data

Throws:

java.lang.Exception - if something goes wrong

hasMoreElements

public boolean hasMoreElements(Instances structure)

returns whether there are more Instance objects in the data.

Parameters:

structure - the structure of the dataset

Returns:

true if there are more Instance objects available

See Also:

nextElement(Instances)

nextElement

public Instance nextElement(Instances dataset)

returns the next element and sets the specified dataset, null if none available.

Parameters:

dataset - the dataset to set for the instance

Returns:

the next Instance

read

public static Instances read(java.lang.String location)
                      throws java.lang.Exception

convencience method for loading a dataset in batch mode.

Parameters:

location - the dataset to load

Returns:

the dataset

Throws:

java.lang.Exception - if loading fails

read

public static Instances read(java.io.InputStream stream)
                      throws java.lang.Exception

convencience method for loading a dataset in batch mode from a stream.

Parameters:

stream - the stream to load the dataset from

Returns:

the dataset

Throws:

java.lang.Exception - if loading fails

read

public static Instances read(Loader loader)
                      throws java.lang.Exception

convencience method for loading a dataset in batch mode.

Parameters:

loader - the loader to get the dataset from

Returns:

the dataset

Throws:

java.lang.Exception - if loading fails

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

for testing only - takes a data file as input.

Parameters:

args - the commandline arguments

Throws:

java.lang.Exception - if something goes wrong

getRevision

public java.lang.String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision