Grid Border Ring Indexes
List row-major cell indexes in an exact inward border ring; out-of-grid layers produce no cells.
Description
List row-major cell indexes in an exact inward border ring; out-of-grid layers produce no cells.
A border ring consists of cells at one minimum edge distance. It is not necessarily an ordered perimeter walk.
When to use this tool
List row-major cell indexes in an exact inward border ring; out-of-grid layers produce no cells.
- Prepare the supplied rows, columns, layer 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 rows, columns, layer. 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.indexes. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
For each row-major cell calculate min(row,column,rows-1-row,columns-1-column). Return its linear index when that value equals layer.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| rows | rows. | Integer from 1 to 128 inclusive |
| columns | columns. | Integer from 1 to 128 inclusive |
| layer | layer. | Integer from 0 to 127 inclusive |
| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.indexes | The indexes list in the ordering and representation described above. |
{
"input": {
"rows": 3,
"columns": 3,
"layer": 0
},
"output": {
"result": {
"indexes": [
0,
1,
2,
3,
5,
6,
7,
8
]
}
}
}Limitations and assumptions
- An unavailable inner layer returns empty. Results are row-major rather than clockwise and no cell is duplicated at corners.
- Coordinate pairs use [row,column] where stated. Masks are nonempty rectangular zero/one matrices of at most 128 rows, 128 columns and 16,384 cells; outside-mask values are unset for the neighborhood operations.
- 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.
- String lists have at most 128 entries of at most 128 code units; matrices have at most 128 rows and columns. Larger numeric lists and parsed JSON have separate bounded budgets. 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
Keep row/column coordinates distinct from x/y pairs and byte offsets. Select the neighborhood metric, outside-mask rule and storage-order convention explicitly; these operations do not infer an image format.
References
Similar or alternative tools
- Grid Mask Border Cells
List set binary mask cells adjacent to a four-neighbor unset/outside position in stable row-major order.
- Grid Crop Coordinate Map
Map source grid coordinates into a half-open crop and retain excluded-coordinate evidence instead of silently clipping.