com.pervasive.datarush.analytics.text

Class TextFrequencyFilter

java.lang.Object

com.pervasive.datarush.operators.AbstractLogicalOperator

com.pervasive.datarush.operators.StreamingOperator

com.pervasive.datarush.operators.ExecutableOperator

com.pervasive.datarush.analytics.text.TextFrequencyFilter

All Implemented Interfaces:

LogicalOperator, PipelineOperator<RecordPort>, RecordPipelineOperator

public class TextFrequencyFilter
extends ExecutableOperator
implements RecordPipelineOperator

Filters a frequency map field. This operator can be used to filter a frequency map. The frequency map can be a WordMap or a NGramMap. The frequencies can be filtered based on whether they fall within the threshold values, whether they are the top n frequencies, or a combination of both. If the output field is unspecified then the original input field will be overwritten.

Constructor Summary

Constructors

Constructor and Description
TextFrequencyFilter() Default constructor.
TextFrequencyFilter(String inputField) Constructor specifying the input field containing the text list and the input field containing the frequency list that will be filtered.
TextFrequencyFilter(String inputField, int totalNumber) Constructor specifying the input field containing the frequency map and sets the total number of top frequencies to keep.
TextFrequencyFilter(String inputField, int min, int max) Constructor specifying the input field containing the frequency map and sets the minimum and maximum threshold of frequencies to keep.

Method Summary

Modifier and Type	Method and Description
protected void	computeMetadata(StreamingMetadataContext ctx) Implementations must adhere to the following contracts
protected void	execute(ExecutionContext ctx) Executes the operator.
RecordPort	getInput() Get the input port of this operator.
String	getInputField() Get the frequency map field to filter.
int	getMaxThreshold() Get the maximum threshold for absolute frequencies when filtering.
int	getMinThreshold() Get the minimum threshold for absolute frequencies when filtering.
RecordPort	getOutput() Get the output port of this operator.
String	getOutputField() Get the output field that will contain the filtered frequency map.
int	getTotalNumber() Get the total number of top frequencies to keep.
void	setInputField(String inputField) Set the frequency map field to filter.
void	setMaxThreshold(int maxThreshold) Set the maximum threshold for absolute frequencies when filtering.
void	setMinThreshold(int minThreshold) Set the minimum threshold for absolute frequencies when filtering.
void	setOutputField(String outputField) Set the output field that will contain the filtered frequency map.
void	setTotalNumber(int totalNumber) Set the total number of top frequencies to keep.

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

cloneForExecution, getNumInputCopies, getPortSettings, handleInactiveOutput

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

TextFrequencyFilter

public TextFrequencyFilter()

Default constructor. Use setInputField(String) to set the name of the frequency map field.

TextFrequencyFilter

public TextFrequencyFilter(String inputField)

Constructor specifying the input field containing the text list and the input field containing the frequency list that will be filtered.

Parameters:

inputField - name of the frequency map field to filter

TextFrequencyFilter

public TextFrequencyFilter(String inputField,
                           int totalNumber)

Constructor specifying the input field containing the frequency map and sets the total number of top frequencies to keep.

Parameters:

inputField - name of the text field to filter

totalNumber - number of highest frequencies to keep

TextFrequencyFilter

public TextFrequencyFilter(String inputField,
                           int min,
                           int max)

Constructor specifying the input field containing the frequency map and sets the minimum and maximum threshold of frequencies to keep.

Parameters:

inputField - name of the text field to filter

min - lowest frequency to keep

max - highest frequency to keep

Method Detail

setInputField

public void setInputField(String inputField)

Set the frequency map field to filter. The field should be a WordMap or NGramMap.

If this field does not exist in the input, or is not of type WordMap or NGramMap, an exception will be thrown at composition time.

Parameters:

inputField - name of the frequency map field to filter

getInputField

public String getInputField()

Get the frequency map field to filter.

Returns:

The name of the frequency map field to filter

setOutputField

public void setOutputField(String outputField)

Set the output field that will contain the filtered frequency map. If unspecified will overwrite the original frequncy map field.

Parameters:

outputField - name of the frequency map output field

getOutputField

public String getOutputField()

Get the output field that will contain the filtered frequency map.

Returns:

The name of the frequency map output field

setMinThreshold

public void setMinThreshold(int minThreshold)

Set the minimum threshold for absolute frequencies when filtering.

Parameters:

minThreshold - minimum frequency to keep

getMinThreshold

public int getMinThreshold()

Get the minimum threshold for absolute frequencies when filtering.

Returns:

minimum frequency to keep

setMaxThreshold

public void setMaxThreshold(int maxThreshold)

Set the maximum threshold for absolute frequencies when filtering.

Parameters:

maxThreshold - maximum frequency to keep

getMaxThreshold

public int getMaxThreshold()

Get the maximum threshold for absolute frequencies when filtering.

Returns:

maximum frequency to keep

setTotalNumber

public void setTotalNumber(int totalNumber)

Set the total number of top frequencies to keep.

Parameters:

totalNumber - number of top frequencies to keep

getTotalNumber

public int getTotalNumber()

Get the total number of top frequencies to keep.

Returns:

number of top frequencies to keep

getInput

public RecordPort getInput()

Get the input port of this operator.

Specified by:

getInput in interface PipelineOperator<RecordPort>

Returns:

input port

getOutput

public RecordPort getOutput()

Get the output port of this operator.

Specified by:

getOutput in interface PipelineOperator<RecordPort>

Returns:

output port

computeMetadata

protected void computeMetadata(StreamingMetadataContext ctx)

Description copied from class: StreamingOperator

Implementations must adhere to the following contracts

General

Regardless of input ports/output port types, all implementations must do the following:

1. Validation. Validation of configuration should always be performed first.
2. Declare parallelizability.. Implementations must declare parallelizability by calling StreamingMetadataContext.parallelize(ParallelismStrategy).

Input record ports

Implementations with input record ports must declare the following:

1. Required data ordering:
Implementations that have data ordering requirements must declare them by calling RecordPort#setRequiredDataOrdering, otherwise data may arrive in any order.
2. Required data distribution (only applies to parallelizable operators):
Implementations that have data distribution requirements must declare them by calling RecordPort#setRequiredDataDistribution, otherwise data will arrive in an unspecified partial distribution.

Note that if the upstream operator's output distribution/ordering is compatible with those required, we avoid a re-sort/re-distribution which is generally a very large savings from a performance standpoint. In addition, some operators may chose to query the upstream output distribution/ordering by calling RecordPort#getSourceDataDistribution and RecordPort#getSourceDataOrdering. These should be viewed as a hints to help chose a more efficient algorithm. In such cases, though, operators must still declare data ordering and data distribution requirements; otherwise there is no guarantee that data will arrive sorted/distributed as required.

Output record ports

Implementations with output record ports must declare the following:

1. Type: Implementations must declare their output type by calling RecordPort#setType.

Implementations with output record ports may declare the following:

1. Output data ordering: Implementations that can make guarantees as to their output ordering may do so by calling RecordPort#setOutputDataOrdering
2. Output data distribution (only applies to parallelizable operators): Implementations that can make guarantees as to their output distribution may do so by calling RecordPort#setOutputDataDistribution

Note that both of these properties are optional; if unspecified, performance may suffer since the framework may unnecessarily re-sort/re-distributed the data.

Input model ports

In general, there is nothing special to declare for input model ports. Models are implicitly duplicated to all partitions when going from non-parallel to parallel operators. The case of a model going from a parallel to a non-parallel node is a special case of a "model reducer" operator. In the case of a model reducer, the downstream operator, must declare the following:

1. Merge handler: Model reducers must declare a merge handler by calling AbstractModelPort#setMergeHandler.

Note that MergeModel is a convenient, re-usable model reducer, parameterized with a merge-handler.

Output model ports

SimpleModelPort's have no associated metadata and therefore there is never any output metadata to declare. PMMLPort's, on the other hand, do have associated metadata. For all PMMLPorts, implementations must declare the following:

1. pmmlModelSpec: Implementations must declare the PMML model spec by calling PMMLPort.setPMMLModelSpec.

Specified by:

computeMetadata in class StreamingOperator

Parameters:

ctx - the context

execute

protected void execute(ExecutionContext ctx)

Description copied from class: ExecutableOperator

Executes the operator. Implementations should adhere to the following contracts:

1. Following execution, all input ports must be at end-of-data.
2. Following execution, all output ports must be at end-of-data.

Specified by:

execute in class ExecutableOperator

Parameters:

ctx - context in which to lookup physical ports bound to logical ports