ST_InteriorRingN

ST_InteriorRingN takes a polygon column and a numeric value (n) and returns a linestring column. The output is the n^th interior ring of the input polygon as a linestring. If there is more than one interior ring, the order of the interior rings is defined by the order in the input polygon. When n=0, the first interior ring is returned. If the index exceeds the number of interior rings in the polygon, null is returned. If the input is a multipolygon null is returned.

Function	Syntax
Python	`interior_ring_n(polygon, n)`
SQL	`ST_InteriorRingN(polygon, n)`

For more details, go to the GeoAnalytics Engine API reference for interior_ring_n.

This function implements the OpenGIS Simple Features Implementation Specification for SQL 1.2.1.

Examples

Python

SQL

Use dark colors for code blocksCopy
from geoanalytics.sql import functions as ST, Polygon

data =[("POLYGON ((10 10, 40 10, 40 40, 10 40, 10 10),"+\
        "(15 15, 20 15, 20 30, 15 30, 15 15), (30 15, 35 15, 35 30, 30 30, 30 15))",),
       ("POLYGON ((20 0, 30 20, 40 0, 20 0))",)]

df = spark.createDataFrame(data, ["wkt"]) \
    .withColumn("polygon", ST.poly_from_text("wkt"))

df.select(ST.interior_ring_n("polygon", 1).alias("interior_ring_n")).show(truncate=False)

Result
Use dark colors for code blocksCopy
+-----------------------------------------------------+
|interior_ring_n                                      |
+-----------------------------------------------------+
|{"paths":[[[30,15],[30,30],[35,30],[35,15],[30,15]]]}|
|NULL                                                 |
+-----------------------------------------------------+

Version table

Release	Notes
1.0.0	Function introduced

ST_InteriorRingN

Examples

Version table

Related topics