stanfordnlp/CoreNLP · error · RuntimeException

: No 1best segmentation available

Error message

: No 1best segmentation available

What it means

JointParsingModel.GenericLatticeScorer.convertItemSpan maps lattice item offsets to character spans using the stored 1-best segmentation (bestSegmentationB). It throws this RuntimeException when that segmentation is null or empty, since span conversion is impossible without it. This surfaces from latticeEdge/latticeHook during lattice-based joint parse-segment decoding.

Solutions

  1. Ensure the segmentation stage runs and produces a non-empty 1-best segmentation before lattice parsing.
  2. Check segmenter output for the sentence; if empty, skip the lattice path or fall back to pipeline parsing.
  3. Verify the model is constructed so bestSegmentationB is set (correct run mode/flags for joint parsing).
  4. Guard the caller: validate bestSegmentationB availability before invoking latticeHook-based parsing.

Example fix

// before
hook = model.latticeHook(lattice); // throws when no 1best segmentation
model.parseLattice(hook);
// after
if (model.has1BestSegmentation()) { // check/ensure segmentation is available
  hook = model.latticeHook(lattice);
  model.parseLattice(hook);
} else {
  // fallback: run standard pipeline parsing
}
Defensive patterns

Strategy: fallback

Validate before calling

// java: ensure 1-best segmentation exists before lattice decoding
if (bestSegmentationB == null || bestSegmentationB.isEmpty()) {
  runSegmentationFirst(sentence); // populate the 1-best segmentation
}

Type guard

// java
if (bestSegmentationB == null || bestSegmentationB.isEmpty()) {
  return null; // caller falls back to non-lattice parsing
}
Item converted = scorer.convertItemSpan(item);

Try / catch

try {
  result = jointModel.latticeParse(lattice);
} catch (RuntimeException e) {
  if (e.getMessage() != null && e.getMessage().endsWith("No 1best segmentation available")) {
    result = standardPipelineParse(words); // fallback: parse without lattice
  } else throw e;
}

Prevention

When it happens

Trigger: Running lattice-based parsing (parse(List<CoreLabel> lattice) with latticeEdge/latticeHook) when the model was never given a 1-best segmentation — bestSegmentationB is null or empty at convertItemSpan time.

Common situations: Invoking the lattice parse path without first running the segmentation step that populates bestSegmentationB; a segmenter that returned zero segments for degenerate/empty input; misconfigured pipeline ordering in the parse-segment model.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/7b9614f3d72307cf. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/international/arabic/parsesegment/JointParsingModel.java:331

                         lexNumRules);
      log.info("ParserPack is " + op.tlpParams.getClass().getName());
      log.info("Lexicon is " + lp.lex.getClass().getName());
    }

    return parse(inputStream);
  }


  /*
   * pparser chart uses segmentation interstices; dparser uses 1best word
   * interstices. Convert between the two here for bparser.
   */
  private static class GenericLatticeScorer implements LatticeScorer {

    @Override
    public Item convertItemSpan(Item item) {
      if(bestSegmentationB == null || bestSegmentationB.isEmpty())
        throw new RuntimeException(this.getClass().getName() + ": No 1best segmentation available");

      item.start = bestSegmentationB.get(item.start).beginPosition();
      item.end = bestSegmentationB.get(item.end - 1).endPosition();
      return item;
    }

    @Override
    public double oScore(Edge edge) {
      final Edge latticeEdge = (Edge) convertItemSpan(new Edge(edge));

      double pOscore = pparser.oScore(latticeEdge);
      double dOscore = dparser.oScore(edge);

      return pOscore + dOscore;
    }

    @Override
    public double iScore(Edge edge) {

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