stanfordnlp/CoreNLP · error · IllegalArgumentException

is not a legal LogPrior.

Error message

 is not a legal LogPrior.

What it means

LogPrior.intToType converts a legacy integer code to a LogPriorType by matching against enum ordinals. If the integer does not match any enum ordinal, an IllegalArgumentException naming the offending int is thrown. This protects the int-based constructor LogPrior(int, double, double) against stale or out-of-range codes.

Solutions

1. Use a valid integer ordinal from LogPriorType.values(), or better, construct with the enum: new LogPrior(LogPriorType.QUADRATIC, sigma, epsilon)
2. Check whether the int came from a saved config produced with a different library version and re-map it
3. Iterate LogPriorType.values() to print valid ordinals and pick the right one

Example fix

// before
LogPrior prior = new LogPrior(7, 1.0, 0.1);
// after
LogPrior prior = new LogPrior(LogPrior.LogPriorType.QUADRATIC, 1.0, 0.1);

int n = LogPriorType.values().length;
if (intPrior < 0 || intPrior >= n)
  throw new IllegalArgumentException("intPrior must be in [0," + (n-1) + "]: " + intPrior);

boolean isValidLogPriorInt(int code) {
  return code >= 0 && code < LogPrior.LogPriorType.values().length;
}

try {
  LogPrior p = new LogPrior(intPrior, sigma, epsilon);
} catch (IllegalArgumentException e) {
  LogPrior p = new LogPrior(LogPrior.LogPriorType.QUADRATIC, sigma, epsilon);
}

When it happens

Trigger: Calling new LogPrior(intPrior, sigma, epsilon) with an integer outside 0..LogPriorType.values().length-1, or an integer serialized under an older version of the enum whose ordinal no longer exists.

Common situations: Persisted model/config files storing numeric prior codes that no longer match the current enum order after the library was upgraded; hand-written integer constants that don't correspond to any ordinal.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• Unknown LogPriorType:
• RuntimeIOException wrapping IOException
• Unsupported subScoreType
• Invalid metricType
• Invalid sub score type

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/d8b952fdaf3481dd. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/classify/LogPrior.java:69

  }

  public LogPrior(int intPrior) {
    this(intPrior, 1.0, 0.1);
  }

  public LogPrior(LogPriorType type) {
    this(type, 1.0, 0.1);
  }

  // why isn't this functionality in enum?
  private static LogPriorType intToType(int intPrior) {
    LogPriorType[] values = LogPriorType.values();
    for (LogPriorType val : values) {
      if (val.ordinal() == intPrior) {
        return val;
      }
    }
    throw new IllegalArgumentException(intPrior + " is not a legal LogPrior.");
  }

  public LogPrior(int intPrior, double sigma, double epsilon) {
    this(intToType(intPrior), sigma, epsilon);
  }

  public LogPrior(LogPriorType type, double sigma, double epsilon) {
    this.type = type;
    if (type != LogPriorType.ADAPT) {
      setSigma(sigma);
      setEpsilon(epsilon);
    }
  }


  // this is the C variable in CSFoo's MM paper C = 1/\sigma^2
//  private double[] regularizationHyperparameters = null;

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