Package weka.core.converters

Class ArffLoader.ArffReader

java.lang.Object

weka.core.converters.ArffLoader.ArffReader

All Implemented Interfaces:

RevisionHandler

Enclosing class:

ArffLoader

public static class ArffLoader.ArffReader
extends Object
implements RevisionHandler

Reads data from an ARFF file, either in incremental or batch mode.

Typical code for batch usage:

 BufferedReader reader =
   new BufferedReader(new FileReader("/some/where/file.arff"));
 ArffReader arff = new ArffReader(reader);
 Instances data = arff.getData();
 data.setClassIndex(data.numAttributes() - 1);
 

Typical code for incremental usage:

 BufferedReader reader =
   new BufferedReader(new FileReader("/some/where/file.arff"));
 ArffReader arff = new ArffReader(reader, 1000);
 Instances data = arff.getStructure();
 data.setClassIndex(data.numAttributes() - 1);
 Instance inst;
 while ((inst = arff.readInstance(data)) != null) {
   data.add(inst);
 }
 

Version:

$Revision: 14509 $

Author:

Eibe Frank (eibe@cs.waikato.ac.nz), Len Trigg (trigg@cs.waikato.ac.nz), fracpete (fracpete at waikato dot ac dot nz)

Constructor Summary

Constructors

Constructor	Description
ArffReader(Reader reader)	Reads the data completely from the reader.
ArffReader(Reader reader, int capacity)
ArffReader(Reader reader, int capacity, boolean batch)	Reads only the header and reserves the specified space for instances.
ArffReader(Reader reader, Instances template, int lines, int capacity, boolean batch, String... fieldSepAndEnclosures)	Initializes the reader without reading the header according to the specified template.
ArffReader(Reader reader, Instances template, int lines, int capacity, String... fieldSepAndEnclosures)	Initializes the reader without reading the header according to the specified template.
ArffReader(Reader reader, Instances template, int lines, String... fieldSepAndEnclosures)	Reads the data without header according to the specified template.

Method Summary

Modifier and Type	Method	Description
Instances	getData()	Returns the data that was read
int	getLineNo()	returns the current line number
boolean	getRetainStringValues()	Get whether to retain the values of string attributes in memory (in the header) when reading incrementally.
String	getRevision()	Returns the revision string.
Instances	getStructure()	Returns the header format
Instance	readInstance(Instances structure)	Reads a single instance using the tokenizer and returns it.
Instance	readInstance(Instances structure, boolean flag)	Reads a single instance using the tokenizer and returns it.
void	setRetainStringValues(boolean retain)	Set whether to retain the values of string attributes in memory (in the header) when reading incrementally.

Methods inherited from class java.lang.Object

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

Constructor Details

ArffReader

public ArffReader(Reader reader)
           throws IOException

Reads the data completely from the reader. The data can be accessed via the getData() method.

Parameters:

reader - the reader to use

Throws:

IOException - if something goes wrong

See Also:

• getData()

ArffReader

public ArffReader(Reader reader,
 int capacity)
           throws IOException

Throws:

IOException

ArffReader

public ArffReader(Reader reader,
 int capacity,
 boolean batch)
           throws IOException

Reads only the header and reserves the specified space for instances. Further instances can be read via readInstance().

Parameters:

reader - the reader to use

capacity - the capacity of the new dataset

batch - true if reading in batch mode

Throws:

IOException - if something goes wrong

IOException - if a problem occurs

See Also:

• getStructure()
• readInstance(Instances)

ArffReader

public ArffReader(Reader reader,
 Instances template,
 int lines,
 String... fieldSepAndEnclosures)
           throws IOException

Reads the data without header according to the specified template. The data can be accessed via the getData() method.

Parameters:

reader - the reader to use

template - the template header

lines - the lines read so far

fieldSepAndEnclosures - an optional array of Strings containing the field separator and enclosures to use instead of the defaults. The first entry in the array is expected to be the single character field separator to use; the remaining entries (if any) are enclosure characters to use.

Throws:

IOException - if something goes wrong

See Also:

• getData()

ArffReader

public ArffReader(Reader reader,
 Instances template,
 int lines,
 int capacity,
 String... fieldSepAndEnclosures)
           throws IOException

Initializes the reader without reading the header according to the specified template. The data must be read via the readInstance() method.

Parameters:

reader - the reader to use

template - the template header

lines - the lines read so far

capacity - the capacity of the new dataset

fieldSepAndEnclosures - an optional array of Strings containing the field separator and enclosures to use instead of the defaults. The first entry in the array is expected to be the single character field separator to use; the remaining entries (if any) are enclosure characters to use.

Throws:

IOException - if something goes wrong

See Also:

• getData()

ArffReader

public ArffReader(Reader reader,
 Instances template,
 int lines,
 int capacity,
 boolean batch,
 String... fieldSepAndEnclosures)
           throws IOException

Initializes the reader without reading the header according to the specified template. The data must be read via the readInstance() method.

Parameters:

reader - the reader to use

template - the template header

lines - the lines read so far

capacity - the capacity of the new dataset

batch - true if the data is going to be read in batch mode

fieldSepAndEnclosures - an optional array of Strings containing the field separator and enclosures to use instead of the defaults. The first entry in the array is expected to be the single character field separator to use; the remaining entries (if any) are enclosure characters to use.

Throws:

IOException - if something goes wrong

See Also:

• getData()

Method Details

getLineNo

public int getLineNo()

returns the current line number

Returns:

the current line number

readInstance

public Instance readInstance(Instances structure)
                      throws IOException

Reads a single instance using the tokenizer and returns it.

Parameters:

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

Returns:

null if end of file has been reached

Throws:

IOException - if the information is not read successfully

readInstance

public Instance readInstance(Instances structure,
 boolean flag)
                      throws IOException

Reads a single instance using the tokenizer and returns it.

Parameters:

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

flag - if method should test for carriage return after each instance

Returns:

null if end of file has been reached

Throws:

IOException - if the information is not read successfully

getStructure

public Instances getStructure()

Returns the header format

Returns:

the header format

getData

public Instances getData()

Returns the data that was read

Returns:

the data

setRetainStringValues

public void setRetainStringValues(boolean retain)

Set whether to retain the values of string attributes in memory (in the header) when reading incrementally.

Parameters:

retain - true if string values are to be retained in memory when reading incrementally

getRetainStringValues

public boolean getRetainStringValues()

Get whether to retain the values of string attributes in memory (in the header) when reading incrementally.

Returns:

true if string values are to be retained in memory when reading incrementally

getRevision

public String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision