st_nrings

Applies to: Databricks Runtime 18.1 and above

Important

Support for GEOGRAPHY values is in Public Preview. Support for GEOMETRY values is generally available.

Returns the total number of rings of the input polygon or multipolygon, including exterior and interior rings. For a multipolygon, returns the sum of all rings across all polygons.

For the corresponding Databricks SQL function, see st_nrings function.

Syntax

from pyspark.databricks.sql import functions as dbf

dbf.st_nrings(col=<col>)

Parameters

Parameter	Type	Description
col	pyspark.sql.Column or str	A Geography or Geometry value.

Examples

Empty 2D polygon GEOMETRY:

from pyspark.databricks.sql import functions as dbf
df = spark.createDataFrame([('POLYGON EMPTY',)], ['wkt'])
df.select(dbf.st_nrings(dbf.st_geomfromtext('wkt')).alias('result')).collect()

[Row(result=0)]

4D polygon GEOGRAPHY with two rings (one exterior, one interior):

from pyspark.databricks.sql import functions as dbf
df = spark.createDataFrame([('POLYGON ZM ((0 0 111 -11,10 0 222 -22,0 10 333 -33,0 0 444 -44),(1 1 555 -55,4 1 666 -66,1 4 777 -77,1 1 888 -88))',)], ['wkt'])
df.select(dbf.st_nrings(dbf.st_geogfromtext('wkt')).alias('result')).collect()

[Row(result=2)]

Empty 3DZ multipolygon GEOMETRY:

from pyspark.databricks.sql import functions as dbf
df = spark.createDataFrame([('MULTIPOLYGON Z EMPTY',)], ['wkt'])
df.select(dbf.st_nrings(dbf.st_geomfromtext('wkt', 4326)).alias('result')).collect()

[Row(result=0)]

Multipolygon GEOGRAPHY with four rings across two polygons:

from pyspark.databricks.sql import functions as dbf
df = spark.createDataFrame([('MULTIPOLYGON (((0 0,10 0,10 10,0 10,0 0),(1 1,4 1,4 4,1 4,1 1),(5 5,6 5,6 6,5 6,5 5)),((20 20,30 20,30 30,20 30,20 20)))',)], ['wkt'])
df.select(dbf.st_nrings(dbf.st_geogfromtext('wkt')).alias('result')).collect()

[Row(result=4)]