Nth chain in polygon

Supported in: Batch, Streaming

Returns the nth ring in a single polygon in the geometry. Indexing is 1-based, and an index of 0 is out-of-bounds. An index equal to 1 returns an external ring. An index greater than 1 returns an internal ring. Returns null for any of the following conditions: geometry isn't a single polygon, a feature collection or geometry collection is provided, index is out-of-bounds, or at least one argument is null.

Expression categories: Geospatial

Declared arguments

• N - Index of the ring to retrieve. Indexing is 1-based, and an index of 0 is out-of-bounds. An index greater than 1 returns an internal ring.
  Expression<Byte | Integer | Long | Short>
• Polygon - Polygon to retrieve the nth ring of.
  Expression<Geometry>

Output type: Geometry

Examples

Example 1: Base case

Argument values:

• N: n
• Polygon: polygon

---

Example 2: Null case

Argument values:

• N: n
• Polygon: polygon

---

Example 3: Edge case

Argument values:

• N: n
• Polygon: polygon

---