ST_IsSimple

Determines if a spatial object does not intersect itself or touch its own boundary at any point.

Behavior type

Syntax

ST_IsSimple( g )

Arguments

g

Spatial object, type GEOMETRY or GEOGRAPHY

Returns

BOOLEAN

Supported data types

Examples

The following examples show how to use ST_IsSimple.

Polygon does not intersect itself:

=> SELECT ST_IsSimple(ST_GeomFromText('POLYGON((-1 2,0 3,1 2,1 -2,-1 2))'));
 ST_IsSimple
--------------
 t
(1 row)

Linestring intersects itself.:

=> SELECT ST_IsSimple(ST_GeographyFromText('LINESTRING(10 10,25 25,26 34.5,
   10 30,10 20,20 10)'));
 St_IsSimple
-------------
 f
(1 row)

Linestring touches its interior at one or more locations:

=> SELECT ST_IsSimple(ST_GeomFromText('LINESTRING(0 0,0 1,1 0,2 1,2 0,0 0)'));
 ST_IsSimple
-------------
 f
(1 row)