Module datarush.analytics
Package com.pervasive.datarush.analytics.text

Class 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 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

      • 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:
          2. 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):
          3. 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