stanfordnlp/CoreNLP · error · IllegalArgumentException

TokensRegexNERAnnotator ERROR: Invalid weight in line in…

Error message

TokensRegexNERAnnotator ERROR: Invalid weight in line  in regexner file : ""!

What it means

When the header defines a 'weight' column, each line's weight is parsed with Double.parseDouble; a non-numeric value throws IllegalArgumentException showing line number, mapping file, and line text. Weights feed pattern scoring and must be valid doubles.

Solutions

Replace the weight on the reported line with a plain double such as 0.0 or 2.5.
Delete the weight column from both header and rows if weights aren't used.
Use '.' decimal separator and no units/symbols ('%', 'N/A').
Verify row alignment — ensure each row's column count matches the header so cells don't shift.

Example fix

// before
[ { word:/CFO/ } ]	PERSON	strong
// after
[ { word:/CFO/ } ]	PERSON	2.0

Defensive patterns

Strategy: validation

Validate before calling

for (String[] row : rows) {
  String w = row[iWeight];
  if (w != null && !w.trim().isEmpty()) Double.parseDouble(w.trim()); // fail early with row context
}

Try / catch

try { annotator = new TokensRegexNERAnnotator(name, props); } catch (IllegalArgumentException e) { if (e.getMessage().contains("Invalid weight")) { fixWeightOnLine(e.getMessage()); } else throw e; }

Prevention

Use plain doubles for weight; avoid spreadsheet exports emitting 'N/A' or '%' symbols
Check row alignment after inserting or removing columns
Validate numeric columns in a CI linter

When it happens

Trigger: A weight column holding non-numeric text such as 'strong', 'N/A', '1,5' (comma decimal), or a percent sign; a shifted row so a non-weight cell lands in the weight column.

Common situations: Hand-edited mapping files with descriptive weights; spreadsheet exports adding 'N/A' for missing values; column misalignment after inserting a column without updating all rows.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/8eeb76b2720e8ade. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/pipeline/TokensRegexNERAnnotator.java:787

      } else {
        overwritableTypes = Collections.emptySet();
      }
      if (iPriority >= 0 && split.length > iPriority) {
        try {
          priority = Double.parseDouble(split[iPriority].trim());
        } catch (NumberFormatException e) {
          throw new IllegalArgumentException("TokensRegexNERAnnotator " + annotatorName
              + " ERROR: Invalid priority in line " + lineCount
              + " in regexner file " + mappingFilename + ": \"" + line + "\"!", e);
        }
      }

      double weight = 0.0;
      if (iWeight >= 0 && split.length > iWeight) {
        try {
          weight = Double.parseDouble(split[iWeight].trim());
        } catch (NumberFormatException e) {
          throw new IllegalArgumentException("TokensRegexNERAnnotator " + annotatorName
              + " ERROR: Invalid weight in line " + lineCount
              + " in regexner file " + mappingFilename + ": \"" + line + "\"!", e);
        }
      }
      int annotateGroup = 0;
      // Get annotate group from input....
      if (iGroup>= 0 && split.length > iGroup) {
        // Which group to take (allow for context)
        String context = split[iGroup].trim();
        try {
          annotateGroup = Integer.parseInt(context);
        } catch (NumberFormatException e) {
          throw new IllegalArgumentException("TokensRegexNERAnnotator " + annotatorName
              + " ERROR: Invalid group in line " + lineCount
              + " in regexner file " + mappingFilename + ": \"" + line + "\"!", e);
        }
      }

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