Equal Value Run Boundary Indexes

Return half-open equal-value run boundaries, including empty input; equality is exact supplied-string equality.

Description

Return half-open equal-value run boundaries, including empty input; equality is exact supplied-string equality.

Run boundaries partition a sequence into consecutive equal-value spans. Half-open bounds can be used directly with ordinary array slices.

When to use this tool

Return half-open equal-value run boundaries, including empty input; equality is exact supplied-string equality.

Prepare the supplied values fields for this operation.
Compare the complete example with the representation used by your own input before carrying the result into another step.

How to use the tool and how it works

Enter values. Use the exact text syntax, units and index conventions explained below.
Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
Read result.runs. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.

Group consecutive entries using Object.is equality and return each run's start and exclusive end in source order.^[1]

Input field	Meaning and representation	Accepted input
values	values.	At most 128 strings, each at most 128 UTF-16 code units

Output field	Interpretation
result	Object containing the named outputs below.
result.runs	The runs list in the ordering and representation described above.

json

{
  "input": {
    "values": [
      "a",
      "a",
      "b"
    ]
  },
  "output": {
    "result": {
      "runs": [
        {
          "start": 0,
          "end": 2
        },
        {
          "start": 2,
          "end": 3
        }
      ]
    }
  }
}

Limitations and assumptions

All runs are returned, including singletons. Object.is distinguishes signed zeros if the input representation preserves them; the tool does not group separated equal values.
Every declared top-level field is required and unexpected fields are rejected. Numeric inputs must be finite; ordinary text fields are bounded to 8,192 UTF-16 code units, with tighter operation-specific limits where stated.
Ordinary string lists have at most 128 entries of at most 128 code units each; numeric lists and matrices have separate bounded size checks. Nonfinite results and excessively large serialized outputs are rejected.
Indexes are zero-based and spans have an exclusive end unless explicitly stated otherwise. A valid false, null or empty-list result is distinct from malformed input.

Alternative or Complementary methods

Use explicit source-index maps when rearranging data or planning missing-value fills. Keep row-major coordinates, cyclic indexes and one-based occurrence numbers distinct, and inspect null donor positions before copying values.

References

Tool behavior and example: Equal Value Run Boundary Indexes — tool.io

Similar or alternative tools

Adjacent Change Indexes
Return indexes whose value differs from the previous supplied string, not CSS change hints or a value transform.
Alternating Sign Run Segmenter
Segment consecutive strictly alternating nonzero signs; zeros and equal adjacent signs break runs.