accessors

CORE

This module contains functions that provide information about internal geometries.

ST_COORDDIM

ST_COORDDIM(geom)

Description

Returns the number of dimensions of the coordinates of Geometry geom.

• geom: Geometry input geom.

Return type

Int

Example

SELECT carto.ST_COORDDIM(carto.ST_MAKEPOINTM(1, 2, 3));
-- 3

ST_DIMENSION

ST_DIMENSION(geom)

Description

Returns the inherent number of dimensions of this Geometry object, which must be less than or equal to the coordinate dimension.

• geom: Geometry input geom.

Return type

Int

Example

SELECT carto.ST_DIMENSION(carto.ST_GEOMFROMWKT("LINESTRING(0 0, 1 1)"));
-- 1

ST_ENVELOPE

ST_ENVELOPE(geom)

Description

Returns a Geometry representing the bounding box of geom.

• geom: Geometry input geom.

Return type

Geometry

Example

SELECT carto.ST_ASTEXT(carto.ST_ENVELOPE(carto.ST_GEOMFROMWKT("LINESTRING(1 1, 2 3)")));
-- POLYGON ((1 1, 1 3, 2 3, 2 1, 1 1))

ST_GEOMETRYN

ST_GEOMETRYN(geom, n)

Description

Returns the n-th Geometry (1-based index) of geom if the Geometry is a GeometryCollection, or geom if it is not.

• geom: Geometry input geom.

• n: Int input number of geom to take.

Return type

Geometry

Example

SELECT carto.ST_ASTEXT(
  carto.ST_GEOMETRYN(
    carto.ST_GEOMFROMWKT(
      "GEOMETRYCOLLECTION(LINESTRING(1 1, 2 3), POINT(0 4), LINESTRING EMPTY)"
    ),
    2
  )
);
-- POINT (0 4)

ST_ISCLOSED

ST_ISCLOSED(geom)

Description

Returns true if geom is a LineString or MultiLineString and its start and end points are coincident. Returns true for all other Geometry types.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISCLOSED(carto.ST_GEOMFROMWKT("LINESTRING(1 1, 2 3, 4 3, 1 1)"));
-- true

ST_ISCOLLECTION

ST_ISCOLLECTION(geom)

Description

Returns true if geom is a GeometryCollection.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISCOLLECTION(
  carto.ST_GEOMFROMWKT(
    "GEOMETRYCOLLECTION(LINESTRING(1 1, 2 3), POINT(0 4)), LINESTRING EMPTY"
  )
);
-- true

ST_ISEMPTY

ST_ISEMPTY(geom)

Description

Returns true if geom is an empty geometry.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISEMPTY(carto.ST_GEOMFROMWKT("LINESTRING EMPTY"));
-- true

ST_ISGEOMFIELD

ST_ISGEOMFIELD(geom)

Description

Returns true if geom is string containing WKT or WKB representation of a geometry.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISGEOMFIELD("LINESTRING(1 1, 2 3)");
-- true

ST_ISRING

ST_ISRING(geom)

Description

Returns true if geom is a LineString or a MultiLineString and is both closed and simple.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISRING(carto.ST_GEOMFROMWKT("LINESTRING(1 1, 2 3, 4 3, 1 1)"));
-- true

ST_ISSIMPLE

ST_ISSIMPLE(geom)

Description

Returns true if geom has no anomalous geometric points, such as self intersection or self tangency.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISSIMPLE(carto.ST_GEOMFROMWKT("LINESTRING(1 1, 2 3, 4 3, 2 3)"));
-- false

ST_ISVALID

ST_ISVALID(geom)

Description

Returns true if the Geometry is topologically valid according to the OGC SFS specification.

• geom: Geometry input geom.

Return type

Boolean

Example

SELECT carto.ST_ISVALID(carto.ST_GEOMFROMWKT("POLYGON((0 0, 1 1, 1 2, 1 1, 0 0))"));
-- false

ST_NUMGEOMETRIES

ST_NUMGEOMETRIES(geom)

Description

If geom is a GeometryCollection, returns the number of geometries. For single geometries, returns 1,

• geom: Geometry input geom.

Return type

Int

Example

SELECT carto.ST_NUMGEOMETRIES(
  carto.ST_GEOMFROMWKT(
    "GEOMETRYCOLLECTION(LINESTRING(1 1, 2 3), POINT(0 4), LINESTRING EMPTY)"
  )
);
-- 3

ST_NUMPOINTS

ST_NUMPOINTS(geom)

Description

Returns the number of vertices in Geometry geom.

• geom: Geometry input geom.

Return type

Int

Example

SELECT carto.ST_NUMPOINTS(carto.ST_GEOMFROMWKT("LINESTRING(1 1, 2 3, 4 4)"));
-- 3

ST_POINTN

ST_POINTN(geom, n)

Description

If geom is a LineString, returns the n-th vertex of geom as a Point. Negative values are counted backwards from the end of the LineString. Returns null if geom is not a LineString.

• geom: Geometry input geom.

• n: Int input number of vertex to take.

Return type

Point

Example

SELECT carto.ST_ASTEXT(
  carto.ST_POINTN(
    carto.ST_GEOMFROMWKT(
      "LINESTRING(1 1, 2 3, 4 4, 3 4)"),
      3
    )
  );
-- POINT (4 4)

ST_X

ST_X(geom)

Description

If geom is a Point, return the X coordinate of that point.

• geom: Geometry input Point.

Return type

Double

Example

SELECT carto.ST_X(carto.ST_GEOMFROMWKT('POINT(-76.09130 18.42750)'));
-- -76.09131

ST_Y

ST_Y(geom)

Description

If geom is a Point, return the Y coordinate of that point.

• geom: Geometry input Point.

Return type

Double

Example

SELECT carto.ST_Y(carto.ST_POINT(-76.09130, 18.42750));
-- 18.4275