org.datavec.api.transform.transform.sequence

Class SequenceOffsetTransform

java.lang.Object

org.datavec.api.transform.transform.sequence.SequenceOffsetTransform

All Implemented Interfaces:

Serializable, ColumnOp, Operation<Schema,Schema>, Transform

public class SequenceOffsetTransform
extends Object
implements Transform

Sequence offset transform takes a sequence, and shifts The values in one or more columns by a specified number of times steps. It has 2 modes of operation (OperationType enum), with respect to the columns it operates on:
InPlace: operations may be performed in-place, modifying the values in the specified columns
NewColumn: operations may produce new columns, with the original (source) columns remaining unmodified

Additionally, there are 2 modes for handling values outside the original sequence (EdgeHandling enum): TrimSequence: the entire sequence is trimmed (start or end) by a specified number of steps
SpecifiedValue: for any values outside of the original sequence, they are given a specified value

Note 1: When specifying offsets, they are done as follows: Positive offsets: move the values in the specified columns to a later time. Earlier time steps are either be trimmed or Given specified values; the last values in these columns will be truncated/removed.

Note 2: Care must be taken when using TrimSequence: for example, if we chain multiple sequence offset transforms on the one dataset, we may end up trimming much more than we want. In this case, it may be better to use SpecifiedValue, (with, for example, NullWritable) and then do a single trim operation (via SequenceTrimTransform) at the end.

Author:

Alex Black

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SequenceOffsetTransform.EdgeHandling
static class	SequenceOffsetTransform.OperationType

Constructor Summary

Constructors

Constructor and Description
SequenceOffsetTransform(List<String> columnsToOffset, int offsetAmount, SequenceOffsetTransform.OperationType operationType, SequenceOffsetTransform.EdgeHandling edgeHandling, Writable edgeCaseValue)

Method Summary

Modifier and Type	Method and Description
String	columnName() Returns a singular column name this op is meant to run on
String[]	columnNames() Returns column names this op is meant to run on
List<Writable>	map(List<Writable> writables) Transform a writable in to another writable
Object	map(Object input) Transform an object in to another object
List<List<Writable>>	mapSequence(List<List<Writable>> sequence) Transform a sequence
Object	mapSequence(Object sequence) Transform a sequence
String	outputColumnName() The output column name after the operation has been applied
String[]	outputColumnNames() The output column names This will often be the same as the input
void	setInputSchema(Schema inputSchema) Set the input schema.
Schema	transform(Schema inputSchema)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.datavec.api.transform.ColumnOp

getInputSchema

Constructor Detail

SequenceOffsetTransform

public SequenceOffsetTransform(List<String> columnsToOffset,
                               int offsetAmount,
                               SequenceOffsetTransform.OperationType operationType,
                               SequenceOffsetTransform.EdgeHandling edgeHandling,
                               Writable edgeCaseValue)

Method Detail

transform

public Schema transform(Schema inputSchema)

Specified by:

transform in interface Operation<Schema,Schema>

setInputSchema

public void setInputSchema(Schema inputSchema)

Description copied from interface: ColumnOp

Set the input schema.

Specified by:

setInputSchema in interface ColumnOp

outputColumnName

public String outputColumnName()

Description copied from interface: ColumnOp

The output column name after the operation has been applied

Specified by:

outputColumnName in interface ColumnOp

Returns:

the output column name

outputColumnNames

public String[] outputColumnNames()

Description copied from interface: ColumnOp

The output column names This will often be the same as the input

Specified by:

outputColumnNames in interface ColumnOp

Returns:

the output column names

columnNames

public String[] columnNames()

Description copied from interface: ColumnOp

Returns column names this op is meant to run on

Specified by:

columnNames in interface ColumnOp

Returns:

columnName

public String columnName()

Description copied from interface: ColumnOp

Returns a singular column name this op is meant to run on

Specified by:

columnName in interface ColumnOp

Returns:

map

public List<Writable> map(List<Writable> writables)

Description copied from interface: Transform

Transform a writable in to another writable

Specified by:

map in interface Transform

Parameters:

writables - the record to transform

Returns:

the transformed writable

mapSequence

public List<List<Writable>> mapSequence(List<List<Writable>> sequence)

Description copied from interface: Transform

Transform a sequence

Specified by:

mapSequence in interface Transform

map

public Object map(Object input)

Description copied from interface: Transform

Transform an object in to another object

Specified by:

map in interface Transform

Parameters:

input - the record to transform

Returns:

the transformed writable

mapSequence

public Object mapSequence(Object sequence)

Description copied from interface: Transform

Transform a sequence

Specified by:

mapSequence in interface Transform