Accessores

Accessores
Anterior	Capítulo 7. Tipos temporales geométricos (Parte 1)	Siguiente

Obtenir la trayectoria o el área atravesada

trajectory(tpoint,unary_union=false) → geo

traversedArea(tgeo,unary_union=false) → geo

Esta función es equivalente a getValues para los valores temporales alphanuméricos. El último argumento indica si se aplica la función PostGIS ST_UnaryUnion para eliminar geometrías redundantes en el resultado. Tenga en cuenta que establecer este argumento como verdadero implica un alto consumo computacional.

SELECT ST_AsText(trajectory(tgeompoint '[Point(0 0)@2001-01-01, Point(0 1)@2001-01-02,
  Point(0 0)@2001-01-03]'));
-- LINESTRING(0 0,0 1,0 0)
SELECT ST_AsText(trajectory(tgeompoint '[Point(0 0)@2001-01-01, Point(0 1)@2001-01-02,
  Point(0 0)@2001-01-03]', true));
-- LINESTRING(0 0,0 1)
SELECT ST_AsText(trajectory(tgeompoint '{[Point(0 0)@2001-01-01, Point(0 1)@2001-01-02),
  [Point(0 1)@2001-01-03, Point(0 0)@2001-01-04)}'));
-- LINESTRING(0 0,0 1)
SELECT ST_AsText(trajectory(tgeompoint 'Interp=Step;{[Point(0 0)@2001-01-01,
  Point(0 1)@2001-01-02], [Point(0 1)@2001-01-03, Point(1 1)@2001-01-04]}'));
-- MULTIPOINT((0 0),(0 1),(1 1))

SELECT ST_AsText(traversedArea(tgeometry '[Point(1 1)@2001-01-01,
  Linestring(1 1,2 2)@2001-01-02, Point(1 1)@2001-01-03]'));
-- GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(1 1,2 2))
SELECT ST_AsText(traversedArea(tgeometry '[Point(1 1)@2001-01-01,
  Linestring(1 1,2 2)@2001-01-02, Point(1 1)@2001-01-03]', true));
-- LINESTRING(1 1,2 2)

Devuelve el centroide como un punto temporal

centroid(tgeo) → tpoint

SELECT asText(centroid(tgeometry '[Point(1 1)@2000-01-01, Linestring(1 1,3 3)@2000-01-02,
  Polygon((1 1,4 4,7 1,1 1))@2000-01-03]'));
-- Interp=Step;[POINT(1 1)@2000-01-01, POINT(2 2)@2000-01-02, POINT(4 2)@2000-01-03]
SELECT asText(centroid(tgeography '[MultiPoint(1 1,4 4,7 1)@2000-01-01, 
  Polygon((1 1,4 4,7 1,1 1))@2000-01-02]'),6);
-- Interp=Step;[POINT(4 2.001727)@2000-01-01, POINT(4 2.001727)@2000-01-02]

Devuelve los valores de las coordenadas X/Y/Z como un número flotante temporal

getX(tpoint) → tfloat

getY(tpoint) → tfloat

getZ(tpoint) → tfloat

SELECT getX(tgeompoint '{Point(1 2)@2001-01-01, Point(3 4)@2001-01-02,
  Point(5 6)@2001-01-03}');
-- {1@2001-01-01, 3@2001-01-02, 5@2001-01-03}
SELECT getX(tgeogpoint 'Interp=Step;[Point(1 2 3)@2001-01-01, Point(4 5 6)@2001-01-02,
  Point(7 8 9)@2001-01-03]');
-- Interp=Step;[1@2001-01-01, 4@2001-01-02, 7@2001-01-03]
SELECT getY(tgeompoint '{Point(1 2)@2001-01-01, Point(3 4)@2001-01-02,
  Point(5 6)@2001-01-03}');
-- {2@2001-01-01, 4@2001-01-02, 6@2001-01-03}
SELECT getY(tgeogpoint 'Interp=Step;[Point(1 2 3)@2001-01-01, Point(4 5 6)@2001-01-02,
  Point(7 8 9)@2001-01-03]');
-- Interp=Step;[2@2001-01-01, 5@2001-01-02, 8@2001-01-03]
SELECT getZ(tgeompoint '{Point(1 2)@2001-01-01, Point(3 4)@2001-01-02,
  Point(5 6)@2001-01-03}');
-- The temporal point must have Z dimension
SELECT getZ(tgeogpoint 'Interp=Step;[Point(1 2 3)@2001-01-01, Point(4 5 6)@2001-01-02,
  Point(7 8 9)@2001-01-03]');
-- Interp=Step;[3@2001-01-01, 6@2001-01-02, 9@2001-01-03]

Devuelve verdadero si el punto temporal no se auto-intersecta espacialmente

isSimple(tpoint) → boolean

Nótese que un punto temporal de conjunto de secuencias es simple si cada una de las secuencias que lo componen es simple.

SELECT isSimple(tgeompoint '[Point(0 0)@2001-01-01, Point(1 1)@2001-01-02,
  Point(0 0)@2001-01-03]');
-- false
SELECT isSimple(tgeompoint '[Point(0 0 0)@2001-01-01, Point(1 1 1)@2001-01-02,
  Point(2 0 2)@2001-01-03, Point(0 0 0)@2001-01-04]');
-- false
SELECT isSimple(tgeompoint '{[Point(0 0 0)@2001-01-01, Point(1 1 1)@2001-01-02],
  [Point(1 1 1)@2001-01-03, Point(0 0 0)@2001-01-04]}');
-- true

Devuelve la longitud atravesada por el punto temporal

length(tpoint) → float

SELECT length(tgeompoint '[Point(0 0 0)@2001-01-01, Point(1 1 1)@2001-01-02]');
-- 1.73205080756888
SELECT length(tgeompoint '[Point(0 0 0)@2001-01-01, Point(1 1 1)@2001-01-02,
  Point(0 0 0)@2001-01-03]');
-- 3.46410161513775
SELECT length(tgeompoint 'Interp=Step;[Point(0 0 0)@2001-01-01,
  Point(1 1 1)@2001-01-02, Point(0 0 0)@2001-01-03]');
-- 0

Devuelve la longitud acumulada atravesada por el punto temporal

cumulativeLength(tpoint) → tfloatSeq

SELECT round(cumulativeLength(tgeompoint '{[Point(0 0)@2001-01-01, Point(1 1)@2001-01-02,
  Point(1 0)@2001-01-03], [Point(1 0)@2001-01-04, Point(0 0)@2001-01-05]}'), 6);
-- {[0@2001-01-01, 1.414214@2001-01-02, 2.414214@2001-01-03],
  [2.414214@2001-01-04, 3.414214@2001-01-05]}
SELECT cumulativeLength(tgeompoint 'Interp=Step;[Point(0 0 0)@2001-01-01,
  Point(1 1 1)@2001-01-02, Point(0 0 0)@2001-01-03]');
-- Interp=Step;[0@2001-01-01, 0@2001-01-03]

Devuelve la velocidad del punto temporal en unidades por segundo

speed(tpoint) → tfloatSeqSet

El punto temporal debe tener interpolación linear

SELECT speed(tgeompoint '{[Point(0 0)@2001-01-01, Point(1 1)@2001-01-02,
  Point(1 0)@2001-01-03], [Point(1 0)@2001-01-04, Point(0 0)@2001-01-05]}') * 3600 * 24;
/* Interp=Step;{[1.4142135623731@2001-01-01, 1@2001-01-02, 1@2001-01-03],
   [1@2001-01-04, 1@2001-01-05]} */
SELECT speed(tgeompoint 'Interp=Step;[Point(0 0)@2001-01-01, Point(1 1)@2001-01-02,
  Point(1 0)@2001-01-03]');
-- ERROR:  The temporal value must have linear interpolation

Devuelve la dirección, es decir, el acimut entre las ubicaciones inicial y final

direction(tpoint) → float

El resultado se expresa en radianes. Es NULL si solo hay una ubicación o si las ubicaciones inicial y final son iguales.

SELECT round(degrees(direction(tgeompoint '[Point(0 0)@2001-01-01,
  Point(-1 -1)@2001-01-02, Point(1 1)@2001-01-03]'))::numeric, 6);
-- 45.000000
SELECT direction(tgeompoint '{[Point(0 0 0)@2001-01-01,
  Point(0 1 1)@2001-01-02, Point(0 1 1)@2001-01-03, Point(0 0 0)@2001-01-04)}');
-- NULL

Devuelve el acimut temporal

azimuth(tpoint) → tfloat

El resultado se expresa en radianes. El azimut es indefinido cuando dos localizaciones sucesivas son iguales y en este caso se añade una brecha de tempo.

SELECT round(degrees(azimuth(tgeompoint '[Point(0 0 0)@2001-01-01,
  Point(1 1 1)@2001-01-02, Point(1 1 1)@2001-01-03, Point(0 0 0)@2001-01-04)')));
-- Interp=Step;{[45@2001-01-01, 45@2001-01-02], [225@2001-01-03, 225@2001-01-04)}

Devuelve la diferencia angular temporal

angularDifference(tpoint) → tfloat

El resultado se expresa en grados.

SELECT round(angularDifference(tgeompoint '[Point(1 1)@2001-01-01, Point(2 2)@2001-01-02,
  Point(1 1)@2001-01-03]'), 3);
-- {0@2001-01-01, 180@2001-01-02, 0@2001-01-03}
SELECT round(degrees(angularDifference(tgeompoint '{[Point(1 1)@2001-01-01,
  Point(2 2)@2001-01-02], [Point(2 2)@2001-01-03, Point(1 1)@2001-01-04]}')), 3);
-- {0@2001-01-01, 0@2001-01-02, 0@2001-01-03, 0@2001-01-04}

Devuelve el rumbo temporal

bearing({tpoint,point},{tpoint,point}) → tfloat

Nótese que esta función no acepta dos puntos geográficos temporales.

SELECT degrees(bearing(tgeompoint '[Point(1 1)@2001-01-01, Point(3 3)@2001-01-03]',
  geometry 'Point(2 2)'));
-- [45@2001-01-01, 0@2001-01-02, 225@2001-01-03]
SELECT round(degrees(bearing(tgeompoint '[Point(0 0)@2001-01-01, Point(2 0)@2001-01-03]',
  tgeompoint '[Point(2 1)@2001-01-01, Point(0 1)@2001-01-03]')), 3);
--  [63.435@2001-01-01, 0@2001-01-02, 296.565@2001-01-03]
SELECT round(degrees(bearing(tgeompoint '[Point(2 1)@2001-01-01, Point(0 1)@2001-01-03]',
  tgeompoint '[Point(0 0)@2001-01-01, Point(2 0)@2001-01-03]')), 3);
-- [243.435@2001-01-01, 116.565@2001-01-03]

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