Package smile.io

Class Arff

java.lang.Object

smile.io.Arff

All Implemented Interfaces:

AutoCloseable

public class Arff
extends Object
implements AutoCloseable

Weka ARFF (attribute relation file format) is an ASCII text file format that is essentially a CSV file with a header that describes the meta-data. ARFF was developed for use in the Weka machine learning software.

A dataset is firstly described, beginning with the name of the dataset (or the relation in ARFF terminology). Each of the variables (or attribute in ARFF terminology) used to describe the observations is then identified, together with their data type, each definition on a single line. The actual observations are then listed, each on a single line, with fields separated by commas, much like a CSV file.

Missing values in an ARFF dataset are identified using the question mark '?'.

Comments can be included in the file, introduced at the beginning of a line with a '%', whereby the remainder of the line is ignored.

A significant advantage of the ARFF data file over the CSV data file is the metadata information.

Also, the ability to include comments ensure we can record extra information about the data set, including how it was derived, where it came from, and how it might be cited.

Constructor Summary

Constructors

Constructor	Description
Arff(Reader reader)	Constructor.
Arff(String path)	Constructor.
Arff(String path, Charset charset)	Constructor.
Arff(Path path)	Constructor.
Arff(Path path, Charset charset)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	close()
String	name()	Returns the name of relation.
DataFrame	read()	Reads all the records.
DataFrame	read(int limit)	Reads a limited number of records.
StructType	schema()	Returns the data schema.
static void	write(DataFrame data, Path path, String relation)	Writes the data frame to an ARFF file.

Methods inherited from class java.lang.Object

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

Constructor Details

Arff

public Arff(String path)
     throws IOException,
ParseException,
URISyntaxException

Constructor.

Parameters:

path - the input file path.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

URISyntaxException - when the file path syntax is wrong.

Arff

public Arff(String path,
 Charset charset)
     throws IOException,
ParseException,
URISyntaxException

Constructor.

Parameters:

path - the input file path.

charset - the charset of file.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

URISyntaxException - when the file path syntax is wrong.

Arff

public Arff(Path path)
     throws IOException,
ParseException

Constructor.

Parameters:

path - the input file path.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

Arff

public Arff(Path path,
 Charset charset)
     throws IOException,
ParseException

Constructor.

Parameters:

path - the input file path.

charset - the charset of file.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

Arff

public Arff(Reader reader)
     throws IOException,
ParseException

Constructor.

Parameters:

reader - the file reader.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

Method Details

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Throws:

IOException

name

public String name()

Returns the name of relation.

Returns:

the name of relation.

schema

public StructType schema()

Returns the data schema.

Returns:

the data schema.

read

public DataFrame read()
               throws IOException,
ParseException

Reads all the records.

Returns:

the data frame.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

read

public DataFrame read(int limit)
               throws IOException,
ParseException

Reads a limited number of records.

Parameters:

limit - the number of records to read.

Returns:

the data frame.

Throws:

IOException - when fails to read the file.

ParseException - when fails to parse the file.

write

public static void write(DataFrame data,
 Path path,
 String relation)
                  throws IOException

Writes the data frame to an ARFF file.

Parameters:

data - the data frame.

path - the output file path.

relation - the relation name of ARFF.

Throws:

IOException - when fails to write the file.