Run Length Record Adjacent Compaction

Description

Compact adjacent exactly equal values by summing exact lengths, not global deduplication.

Run-length records represent repeated observations without expanding them. Each record pairs a literal string value with a positive exact integer length; neighboring equal values can be valid but noncompact. Expanded offsets count observations rather than run records, and half-open ranges include their start while excluding their end.

Compact adjacent exactly equal values by summing exact lengths, not global deduplication.

When to use this tool

Use this tool to compact adjacent exactly equal values by summing exact lengths, not global deduplication.

How to use the tool and how it works

Enter runsJson using the definitions below. Serialize JSON text fields in the decoded shape shown below.
Run the operation. Resolve input-format errors before interpreting an output.
Read result.runs, using the stated boundary, ordering, sign and absence conventions.

Scan source runs, add the exact length to the previous output run when values are equal, otherwise append a new run.^[1]

Input field	Meaning and units	Accepted input
runsJson	JSON array of {value,length} records: literal string value and positive exact decimal-string length.	Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply.

These decoded structures show the examples inside JSON text fields. Supply their serialized JSON strings as input.

json

{
  "runsJson": [
    {
      "value": "a",
      "length": "3"
    },
    {
      "value": "a",
      "length": "2"
    },
    {
      "value": "b",
      "length": "4"
    }
  ]
}

Output field	Interpretation
result	Object containing the fields below.
result.runs	Resulting {value,length} records, with exact positive decimal lengths and the stated compaction policy.

json

{
  "input": {
    "runsJson": "[{\"value\": \"a\", \"length\": \"3\"}, {\"value\": \"a\", \"length\": \"2\"}, {\"value\": \"b\", \"length\": \"4\"}]"
  },
  "output": {
    "result": {
      "runs": [
        {
          "value": "a",
          "length": "5"
        },
        {
          "value": "b",
          "length": "4"
        }
      ]
    }
  }
}

Limitations and assumptions

Only adjacent equal values merge; separated equal values keep their positions in the sequence.
Run records contain string value and positive length as exact decimal integer text. Lengths and offset inputs support up to 256 decimal digits before operation-specific checks; results use decimal text and do not expand the repeated observations.
Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
Ordinary numeric outputs must be finite and within safe-integer magnitude. Exact large lengths/counts use decimal strings. Original record indexes and code-unit positions are zero-based; span ends are exclusive unless stated otherwise.

Alternative or Complementary methods

Use compaction for a canonical adjacent-run layout and boundary-aware operations when provenance matters. Retain exact decimal lengths rather than converting long totals to floating-point numbers.

References

Tool behavior and example: Run Length Record Adjacent Compaction — tool.io

Similar or alternative tools

Run Length Record Aligned Pair Spans
Run lengths are positive exact integer decimal strings with literal string values, never expanded; align two equal-total encoded sequences at every source boundary, with paired values and exact logical spans.
Run Length Record Boundary Transition Table
Run lengths are positive exact integer decimal strings with literal string values, never expanded; report encoded run boundaries with exact logical offsets and equal-versus-changed neighboring values.