stanfordnlp/CoreNLP · error · IllegalArgumentException

to length:" + to.length + " from length:" + from.length

Error message

to length:" + to.length + " from length:" + from.length

What it means

The float[] overload of ArrayMath.pairwiseAddInPlace requires both arrays to have identical length, since it adds from[i] into to[i] element-wise. A length mismatch means the operation is undefined, so it throws IllegalArgumentException immediately with both lengths in the message.

Solutions

1. Check to.length == from.length before calling, or pad/trim the shorter array.
2. Rebuild one of the arrays from the same feature space/model version as the other.
3. Catch IllegalArgumentException and log both lengths to identify which pipeline stage produced the mismatched vector.

Example fix

// before
ArrayMath.pairwiseAddInPlace(a, b); // a.length=10, b.length=9
// after
if (a.length == b.length) ArrayMath.pairwiseAddInPlace(a, b);

if (to.length != from.length) throw new IllegalArgumentException("cannot pairwise-add float arrays: " + to.length + " vs " + from.length);

boolean sameLength(float[] a, float[] b) { return a.length == b.length; }

try { ArrayMath.pairwiseAddInPlace(to, from); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("to length:")) { /* resize or abort */ } else throw e; }

When it happens

Trigger: Calling ArrayMath.addInPlace or pairwiseAddInPlace(float[], float[]) with arrays produced from different models, different feature counts, or truncated/sliced arrays of unequal size.

Common situations: Mixing feature vectors from different feature alphabets; loading weights checkpointed with an older model version whose dimensionality changed.

Related errors

• Arrays do not have the same length.
• Array must be sorted!
• dim should be an array of size 2.
• Vector of incorrect size passed to applyInitialHessian in…
• Word vectors file has dimension too small for requested…

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/04e5b2c977a6c852. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/math/ArrayMath.java:302

    return result;
  }

  /**
   * raises each entry in array a by power c
   */
  public static float[] pow(float[] a, float c) {
    float[] result = new float[a.length];
    for (int i = 0; i < a.length; i++) {
      result[i] = (float) Math.pow(a[i], c);
    }
    return result;
  }

  // OPERATIONS WITH TWO ARRAYS - DESTRUCTIVE

  public static void pairwiseAddInPlace(float[] to, float[] from) {
    if (to.length != from.length) {
      throw new IllegalArgumentException("to length:" + to.length + " from length:" + from.length);
    }
    for (int i = 0; i < to.length; i++) {
      to[i] += from[i];
    }
  }

  /**
   * Add the two 1d arrays in place of {@code to}.
   *
   * @throws java.lang.IllegalArgumentException If {@code to} and {@code from} are not of the same dimensions
   */
  public static void pairwiseAddInPlace(double[] to, double[] from) {
    if (to.length != from.length) {
      throw new IllegalArgumentException("to length:" + to.length + " from length:" + from.length);
    }
    for (int i = 0; i < to.length; i++) {
      to[i] += from[i];
    }

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