ST_GeometryN

ST_GeometryN takes a geometry column and a numeric column or value (n) and returns a geometry column. The output column contains the n^th single-part geometry from a multipart geometry. When n=0, the first single-part geometry is returned. If the n^th geometry doesn't exist, null is returned.

Function	Syntax
Python	`geometry_n(geometry, n)`
SQL	`ST_GeometryN(geometry, n)`

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

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

Examples

Python

SQL

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from geoanalytics.sql import functions as ST, Polygon

data = [
    (Polygon([[[40,120],[90,120],[90,150],[40,150],[40,120]],[[50,130],[60,130],[60,140],[50,140],[50,130]]]),),
    (Polygon([[[20,0],[30,20],[40,0],[20,0]]]),)
]

df = spark.createDataFrame(data, ["polygon"])

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

Result
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+----------------------------------------------------------+
|geometry_n                                                |
+----------------------------------------------------------+
|{"rings":[[[50,130],[60,130],[60,140],[50,140],[50,130]]]}|
|NULL                                                      |
+----------------------------------------------------------+

Version table

Release	Notes
1.0.0	Function introduced

ST_GeometryN

Examples

Version table

Related topics