com.pervasive.datarush.operators.io.textfile

Class WriteARFF

java.lang.Object

com.pervasive.datarush.operators.AbstractLogicalOperator

com.pervasive.datarush.operators.CompositeOperator

com.pervasive.datarush.operators.io.AbstractWriter

com.pervasive.datarush.operators.io.textfile.AbstractTextWriter

com.pervasive.datarush.operators.io.textfile.WriteARFF

All Implemented Interfaces:

LogicalOperator, RecordSinkOperator, SinkOperator<RecordPort>

public class WriteARFF
extends AbstractTextWriter

Write files using the Attribute-Relation File Format (ARFF). ARFF supportes both sparse and dense formats. This can be specified by using the setFormatMode(ARFFMode) method. The default mode is sparse. When the input data is highly sparse, the sparse mode can save space since it only writes non-zero values. However, if the data is not very sparse, using sparse mode can actually cause the resultant file to be larger; use dense mode for dense data.

Note that when writing sparse data that contains enumerated types, the zero ordinal category will always be treated as sparse and so will not appear in the output file. This is normal and expected behavior. The enumerated type is captured in the meta-data. When the file is read, the zero ordinal values will be restored as expected.

Field Summary

Fields inherited from class com.pervasive.datarush.operators.io.textfile.AbstractTextWriter

encodingProps

Fields inherited from class com.pervasive.datarush.operators.io.AbstractWriter

input, options

Constructor Summary

Constructors

Constructor and Description
WriteARFF() Writes ARFF data to an empty target with default settings.
WriteARFF(ByteSink target, WriteMode mode) Writes ARFF data to the specified target sink in the given mode.
WriteARFF(Path path, WriteMode mode) Writes ARFF data to the specified path in the given mode, using default settings.
WriteARFF(String path, WriteMode mode) Writes ARFF data to the specified path in the given mode, using default settings.

Method Summary

Modifier and Type	Method and Description
void	addComment(String comment) Add a comment line that will be written to the ARFF meta-data section of the file.
protected DataFormat	computeFormat(CompositionContext ctx) Determines the data format for the target.
List<String>	getComments() Gets the comments lines current set to be written.
char	getFieldDelimiter() Get the configured field delimiter property value.
ARFFMode	getFormatMode() Get the value of the mode property.
String	getRecordSeparator() Get the record separator.
String	getRelationName() Get the value of the relation name property.
TextRecord	getSchema() Get the configured schema for this reader instance.
void	setComments(List<String> comments) Set the comments lines to write to the ARFF meta-data section of the file.
void	setFieldDelimiter(char delimiter) Set the field delimiter to use when writing the file contents.
void	setFormatMode(ARFFMode mode) Set the mode with which to write the file.
void	setRecordSeparator(String separator) Set the record separator.
void	setRelationName(String relationName) Set the relation name attribute.
void	setSchema(TextRecord schema) Set the schema to use for the provided data.

Methods inherited from class com.pervasive.datarush.operators.io.textfile.AbstractTextWriter

getCharset, getCharsetName, getEncodeBuffer, getEncoding, getErrorAction, getReplacement, setCharset, setCharsetName, setEncodeBuffer, setEncoding, setErrorAction, setReplacement

Methods inherited from class com.pervasive.datarush.operators.io.AbstractWriter

compose, getFormatOptions, getInput, getMode, getSaveMetadata, getTarget, getWriteBuffer, getWriteOnClient, getWriteSingleSink, isIgnoreSortOrder, setFormatOptions, setIgnoreSortOrder, setMode, setSaveMetadata, setTarget, setTarget, setTarget, setWriteBuffer, setWriteOnClient, setWriteSingleSink

Methods inherited from class com.pervasive.datarush.operators.AbstractLogicalOperator

disableParallelism, getInputPorts, getOutputPorts, newInput, newInput, newOutput, newRecordInput, newRecordInput, newRecordOutput, notifyError

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.pervasive.datarush.operators.LogicalOperator

disableParallelism, getInputPorts, getOutputPorts

Constructor Detail

WriteARFF

public WriteARFF()

Writes ARFF data to an empty target with default settings. The target must be set before execution or an error will be raised.

See Also:

AbstractWriter.setTarget(ByteSink)

WriteARFF

public WriteARFF(String path,
                 WriteMode mode)

Writes ARFF data to the specified path in the given mode, using default settings.

If the writer is parallelized, this is interpreted as a directory in which each partition will write a fragment of the entire input stream. Otherwise, it is interpreted as the file to write.

Parameters:

path - the path to which to write

mode - how to handle existing files

WriteARFF

public WriteARFF(Path path,
                 WriteMode mode)

Writes ARFF data to the specified path in the given mode, using default settings.

If the writer is parallelized, this is interpreted as a directory in which each partition will write a fragment of the entire input stream. Otherwise, it is interpreted as the file to write.

Parameters:

path - the path to which to write

mode - how to handle existing files

WriteARFF

public WriteARFF(ByteSink target,
                 WriteMode mode)

Writes ARFF data to the specified target sink in the given mode.

The writer can only be parallelized if the sink is fragmentable. In this case, each partition will be written as an independent sink. Otherwise, the writer will run non-parallel.

Parameters:

target - the sink to which to write

mode - how to handle an existing sink

Method Detail

getRelationName

public String getRelationName()

Get the value of the relation name property.

Returns:

relation name

setRelationName

public void setRelationName(String relationName)

Set the relation name attribute. In ARFF, the relation name is captured in the meta-data with the tag @attribute.

Parameters:

relationName - name of the relation

addComment

public void addComment(String comment)

Add a comment line that will be written to the ARFF meta-data section of the file. Multiple comments may be added. They will be written in the order provided.

Parameters:

comment - a line of commentary to add to the output file

setComments

public void setComments(List<String> comments)

Set the comments lines to write to the ARFF meta-data section of the file.

Parameters:

comments - lines of commentary to add to the output file

getComments

public List<String> getComments()

Gets the comments lines current set to be written.

Returns:

the lines of commentary to add to the output file

setRecordSeparator

public void setRecordSeparator(String separator)

Set the record separator. This string will be output at the end of each record written. The default value is the system dependent record separator.

Parameters:

separator - text separating records

getRecordSeparator

public String getRecordSeparator()

Get the record separator.

Returns:

record separator

getFormatMode

public ARFFMode getFormatMode()

Get the value of the mode property.

Returns:

write mode

setFormatMode

public void setFormatMode(ARFFMode mode)

Set the mode with which to write the file. The supported modes are SPARSE and DENSE.

Parameters:

mode - write mode; either sparse or dense

getSchema

public TextRecord getSchema()

Get the configured schema for this reader instance.

Returns:

configured schema (may be null)

setFieldDelimiter

public void setFieldDelimiter(char delimiter)

Set the field delimiter to use when writing the file contents. A single quote is used by default. The only supported values are a single quote and a double quote.

Parameters:

delimiter - the delimiter to used for field values containing spaces

getFieldDelimiter

public char getFieldDelimiter()

Get the configured field delimiter property value.

Returns:

configured field delimiter

setSchema

public void setSchema(TextRecord schema)

Set the schema to use for the provided data. A schema is not required. If a schema is not provided, a default schema will be constructed using default formatting options for all fields. A schema is useful to explicitly specify the formatting options for fields. This is especially useful for date and timestamp types, but is applicable to all types.

Parameters:

schema - definition of field ordering, names, types and formats

computeFormat

protected DataFormat computeFormat(CompositionContext ctx)

Description copied from class: AbstractWriter

Determines the data format for the target. The returned format is used during composition to construct a WriteSink operator. If an implementation supports schema discovery, it must be performed in this method.

Specified by:

computeFormat in class AbstractWriter

Parameters:

ctx - the composition context for the current invocation of AbstractWriter.compose(CompositionContext)

Returns:

the target format to use