stanfordnlp/CoreNLP · error · IllegalArgumentException

Not enough columns for format

Error message

Not enough columns for format ${format}

What it means

formatCsv builds output strings from a user-supplied format where $N refers to the Nth tab-separated column of the input line. If the format references a column index beyond the number of fields actually present, it throws IllegalArgumentException("Not enough columns for format ..."), reporting the format string.

Solutions

  1. Ensure input lines contain at least as many tab-separated columns as the highest $N in the csvFormat
  2. Lower the column indices in -csvFormat to reference existing columns
  3. Check the input for rows with missing trailing fields

Example fix

// before
props.setProperty("csvFormat", "$3\t$4"); // input only has 3 columns (0-2)
// after
props.setProperty("csvFormat", "$2\t$3"); // wait: use indices < fields.length, e.g. $0\t$1
Defensive patterns

Strategy: validation

Validate before calling

int maxIdx = 0; Matcher m = Pattern.compile("\\$(\\d)").matcher(csvFormat); while (m.find()) maxIdx = Math.max(maxIdx, Integer.parseInt(m.group(1))); if (fields.length <= maxIdx) throw new IllegalStateException("csvFormat needs " + (maxIdx+1) + " columns, line has " + fields.length);

Type guard

null

Try / catch

try { String out = testExamples(...); } catch (IllegalArgumentException e) { log.error("csvFormat references missing column: " + e.getMessage()); }

Prevention

When it happens

Trigger: Calling testExamples/testExample with a -csvFormat like "$4\t$5" on an input line that only has 3 tab-separated columns, or a format index >= fields.length.

Common situations: csvFormat written for a training file with more columns than the test/prediction input; input lines with missing trailing columns; format indices being 1-based vs 0-based confusion (format uses digit characters mapped directly, field = digit).

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/51d31f7bb2f2d9d7. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/classify/ColumnDataClassifier.java:803

      } else {
        writeAnswer(example, answer, dist);
      }
    }
    updatePerformanceStatistics(example, answer, dist, contingency, cl, sim);
  }

  private String formatCsv(String format, String[] fields, String answer) {
    StringBuilder out = new StringBuilder();
    for (int i = 0, len = format.length(); i < len; i++) {
      char ch = format.charAt(i);
      if (ch == '%' && i + 1 < len) {
        char ch2 = format.charAt(i + 1);
        if (ch2 >= '0' && ch2 <= '9') {
          int field = ch2 - '0';
          if (field < fields.length) {
            out.append(fields[field]);
          } else {
            throw new IllegalArgumentException("Not enough columns for format " + format);
          }
        } else if (ch2 == 'c') {
          if (answer != null) {
            out.append(answer);
          } else if (globalFlags.goldAnswerColumn < fields.length) {
            out.append(fields[globalFlags.goldAnswerColumn]);
          } else {
            out.append("Class");
          }
        } else if (ch2 == 'n') {
          out.append('\n');
        } else {
          throw new IllegalArgumentException("Unrecognized format specification in " + format);
        }
        i++; // have also dealt with next character giving format
      } else {
        out.append(ch);
      }

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