Description
Mark start when previous differs from current and end when current differs from next.
A run is a consecutive group of equal values. Its internal adjacencies and boundary relationships differ from counts of distinct values across a whole list.
Mark start when previous differs from current and end when current differs from next.
When to use this tool
Use List Run Boundary Two Neighbor Mask when you need one run boundary or adjacency calculation.
How to use the tool and how it works
- Enter previous, current, next. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read start, end, singleton. Inspect start, end, singleton before interpreting the associated values.
Mark start when previous differs from current and end when current differs from next. Mark singleton when both comparisons differ.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| previous | Previous | Required. Text; maximum UTF-16 length 8192. |
| current | Current | Required. Text; maximum UTF-16 length 8192. |
| next | Next | Required. Text; maximum UTF-16 length 8192. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| start | Start | Required. Boolean. |
| end | End | Required. Boolean. |
| singleton | Singleton | Required. Boolean. |
{
"input": {
"previous": "a",
"current": "b",
"next": "c"
},
"output": {
"start": true,
"end": true,
"singleton": true
}
}Limitations and assumptions
- All neighbors are explicit values; list endpoints and missing-neighbor conventions must be resolved externally.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Alternative or Complementary methods
Use a complete run-length scan when maximal runs and their values need to be constructed or verified.
References
Similar or alternative tools
- List Run Length One Boundary Update
Compare leftValue and rightValue exactly.
- Duplicate Run Internal Edge Count
Sum runLength minus one across positive integer runLengths using exact integer intermediates, then return the numeric internalEdges.