OnePassDataIndexer (Apache OpenNLP Tools 1.9.5 API)
Date: 2026-06-18

opennlp.tools.ml.model

## Class OnePassDataIndexer

- java.lang.Object
- - opennlp.tools.ml.model.AbstractDataIndexer
  - - opennlp.tools.ml.model.OnePassDataIndexer

- All Implemented Interfaces:
    DataIndexer
  Direct Known Subclasses:
    OnePassRealValueDataIndexer

      public class OnePassDataIndexer
      extends AbstractDataIndexer

  An indexer for maxent model data which handles cutoffs for uncommon contextual predicates and provides a unique integer index for each of the predicates.

- - ### Field Summary

    - ### Fields inherited from class opennlp.tools.ml.model.AbstractDataIndexer

      `CUTOFF_DEFAULT, CUTOFF_PARAM, SORT_DEFAULT, SORT_PARAM`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `OnePassDataIndexer()`

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `index(ObjectStream<Event> eventStream)` Performs the data indexing.

    - ### Methods inherited from class opennlp.tools.ml.model.AbstractDataIndexer

      `getContexts, getNumEvents, getNumTimesEventsSeen, getOutcomeLabels, getOutcomeList, getPredCounts, getPredLabels, getValues, init`

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### OnePassDataIndexer

          public OnePassDataIndexer()

  - ### Method Detail

    - #### index

          public void index(ObjectStream<Event> eventStream)
                     throws IOException

      Description copied from interface: `DataIndexer`
      Performs the data indexing. Make sure the init(...) method is called first.
      Parameters:
        `eventStream` - a stream of events
      Throws:
        `IOException`

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