weka.core.converters
Class CSVLoader

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

All Implemented Interfaces:

BatchLoader, Loader, java.io.Serializable

public class CSVLoader

extends AbstractLoader

implements BatchLoader

Reads a text file that is comma or tab delimited..

Version:

$Revision: 1.4 $

Author:

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

See Also:

Loader, Serialized Form

Field Summary

private FastVector	m_cumulativeInstances Holds instances accumulated so far
private FastVector	m_cumulativeStructure A list of hash tables for accumulating nominal values during parsing.
protected java.io.File	m_sourceFile Holds the source of the data set.
protected Instances	m_structure Holds the determined structure (header) of the data set.

Fields inherited from class weka.core.converters.AbstractLoader

BATCH, INCREMENTAL, m_retrieval, NONE

Constructor Summary

CSVLoader()

Method Summary

private void	checkStructure(FastVector current) Checks the current instance against what is known about the structure of the data set so far.
Instances	getDataSet() Return the full data set.
private FastVector	getInstance(java.io.StreamTokenizer tokenizer) Attempts to parse a line of the data set.
Instance	getNextInstance() CSVLoader is unable to process a data set incrementally.
Instances	getStructure() Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
java.lang.String	globalInfo() Returns a string describing this attribute evaluator
private void	initTokenizer(java.io.StreamTokenizer tokenizer) Initializes the stream tokenizer
static void	main(java.lang.String[] args) Main method.
private void	readHeader(java.io.StreamTokenizer tokenizer) Assumes the first line of the file contains the attribute names.
private void	readStructure(java.io.StreamTokenizer st)
void	reset() Resets the loader ready to read a new data set
void	setSource(java.io.File file) Resets the Loader object and sets the source of the data set to be the supplied File object.

Methods inherited from class weka.core.converters.AbstractLoader

getRetrieval, setRetrieval, setSource

Methods inherited from class java.lang.Object

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

Field Detail

m_structure

protected Instances m_structure

Holds the determined structure (header) of the data set.

m_sourceFile

protected java.io.File m_sourceFile

Holds the source of the data set.

m_cumulativeStructure

private FastVector m_cumulativeStructure

A list of hash tables for accumulating nominal values during parsing.

m_cumulativeInstances

private FastVector m_cumulativeInstances

Holds instances accumulated so far

Constructor Detail

CSVLoader

public CSVLoader()

Method Detail

globalInfo

public java.lang.String globalInfo()

Returns a string describing this attribute evaluator

Returns:

a description of the evaluator suitable for displaying in the explorer/experimenter gui

reset

public void reset()

Resets the loader ready to read a new data set

setSource

public 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.

Specified by:

setSource in interface Loader

Overrides:

setSource in class AbstractLoader

Parameters:

file - the source file.

Throws:

java.io.IOException - if an error occurs

getStructure

public 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.

Specified by:

getStructure in interface Loader

Specified by:

getStructure in class AbstractLoader

Returns:

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

Throws:

java.io.IOException - if an error occurs

readStructure

private void readStructure(java.io.StreamTokenizer st)
                    throws java.io.IOException

Throws:

java.io.IOException

getDataSet

public 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 method should do so before processing the rest of the data set.

Specified by:

getDataSet in interface Loader

Specified by:

getDataSet in class AbstractLoader

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

getNextInstance

public Instance getNextInstance()
                         throws java.io.IOException

CSVLoader is unable to process a data set incrementally.

Specified by:

getNextInstance in interface Loader

Specified by:

getNextInstance in class AbstractLoader

Returns:

never returns without throwing an exception

Throws:

java.io.IOException - always. CSVLoader is unable to process a data set incrementally.

getInstance

private FastVector getInstance(java.io.StreamTokenizer tokenizer)
                        throws java.io.IOException

Attempts to parse a line of the data set.

Parameters:

tokenizer - the tokenizer

Returns:

a FastVector containg String and Double objects representing the values of the instance.

Throws:

java.io.IOException - if an error occurs

    private_normal_behavior
      requires: tokenizer != null;
      ensures: \result  != null;
  also
    private_exceptional_behavior
      requires: tokenizer == null
                || (* unsucessful parse *);
      signals: (IOException);
 

checkStructure

private void checkStructure(FastVector current)
                     throws java.lang.Exception

Checks the current instance against what is known about the structure of the data set so far. If there is a nominal value for an attribute that was beleived to be numeric then all previously seen values for this attribute are stored in a Hashtable.

Parameters:

current - a FastVector value

Throws:

java.lang.Exception - if an error occurs

    private_normal_behavior
      requires: current != null;
  also
    private_exceptional_behavior
      requires: current == null
                || (* unrecognized object type in current *);
      signals: (Exception);
 

readHeader

private void readHeader(java.io.StreamTokenizer tokenizer)
                 throws java.io.IOException

Assumes the first line of the file contains the attribute names. Assumes all attributes are real (Reading the full data set with getDataSet will establish the true structure).

Parameters:

tokenizer - a StreamTokenizer value

Throws:

java.io.IOException - if an error occurs

    private_normal_behavior
      requires: tokenizer != null;
      modifiable: m_structure;
      ensures: m_structure != null;
  also
    private_exceptional_behavior
      requires: tokenizer == null
                || (* unsucessful parse *);
      signals: (IOException);
 

initTokenizer

private void initTokenizer(java.io.StreamTokenizer tokenizer)

Initializes the stream tokenizer

Parameters:

tokenizer - the tokenizer to initialize

main

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

Main method.

Parameters:

args - should contain the name of an input file.