postgresql----幾何類型和函數

postgresql支援的幾何類型如下表：

名字	存儲空間	描述	表現形式
point	16位元組	平面上的點	(x,y)
line	32位元組	直線	{A,B,C}
lseg	32位元組	線段	((x1,y1),(x2,y2))
box	32位元組	矩形	((x1,y1),(x2,y2))
path	16+16n位元組	閉合路徑	((x1,y1),...)
path	16+16n位元組	開放路徑	[(x1,y1),...]
polygon	40+16n位元組	多邊形	((x1,y1),...)
circle	24位元組	圓	<(x,y),r>

示例：

test=# select point'(1,1)';
 point 
-------
 (1,1)
(1 row)

test=# select line'{1,1,1}';
  line   
---------
 {1,1,1}
(1 row)

test=# select lseg'(1,1),(2,2)';
     lseg      
---------------
 [(1,1),(2,2)]
(1 row)

test=# select box'(1,1),(2,2)';
     box     
-------------
 (2,2),(1,1)
(1 row)

test=# select path'(1,1),(2,2),(2,1)';
        path         
---------------------
 ((1,1),(2,2),(2,1))
(1 row)

test=# select path'[(1,1),(2,2),(2,1)]';
        path         
---------------------
 [(1,1),(2,2),(2,1)]
(1 row)

test=# select polygon'((1,1),(2,2),(2,1))';
       polygon       
---------------------
 ((1,1),(2,2),(2,1))
(1 row)

test=# select circle'<(0,0),1>';
  circle   
-----------
 <(0,0),1>
(1 row)
           

操作符

操作符	描述	示例	結果
+	平移	select box '((0,0),(1,1))' + point '(2.0,0)';	(3,1),(2,0)
-	平移	select box '((0,0),(1,1))' - point '(2.0,0)';	(-1,1),(-2,0)
*	伸縮/旋轉	select box '((0,0),(1,1))' * point '(2.0,0)';	(2,2),(0,0)
/	伸縮/旋轉	select box '((0,0),(2,2))' / point '(2.0,0)';	(1,1),(0,0)
#	交點或者交面	select box'((1,-1),(-1,1))' # box'((1,1),(-1,-1))';	(1,1),(-1,-1)
#	path或polygon的頂點數	select #path'((1,1),(2,2),(2,1))';	3
@-@	長度或周長	select @-@ path'((1,1),(2,2),(2,1))';	3.41421356237309
@@	中心	select @@ circle'<(0,0),1>';	(0,0)
##	第一個操作數和第二個操作數的最近點	select point '(0,0)' ## lseg '((2,0),(0,2))';	(1,1)
<->	間距	select circle '<(0,0),1>' <-> circle '<(5,0),1>';	3
&&	是否有重疊	select box '((0,0),(1,1))' && box '((0,0),(2,2))';	t
<<	是否嚴格在左	select circle '((0,0),1)' << circle '((5,0),1)';	t
>>	是否嚴格在右	select circle '((0,0),1)' >> circle '((5,0),1)';	f
&<	是否沒有延伸到右邊	select box '((0,0),(1,1))' &< box '((0,0),(2,2))';	t
&>	是否沒有延伸到左邊	select box '((0,0),(3,3))' &> box '((0,0),(2,2))';	t
<<|	是否嚴格在下	select box '((0,0),(3,3))' <<| box '((3,4),(5,5))';	t
|>>	是否嚴格在上	select box '((3,4),(5,5))' |>> box '((0,0),(3,3))';	t
&<|	是否沒有延伸到上面	select box '((0,0),(1,1))' &<| box '((0,0),(2,2))';	t
|&>	是否沒有延伸到下面	select box '((0,0),(3,3))' |&> box '((0,0),(2,2))';	t
<^	是否低于（允許接觸）	select box '((0,0),(3,3))' <^ box '((3,3),(4,4))';	t
>^	是否高于（允許接觸）	select box '((0,0),(3,3))' >^ box '((3,3),(4,4))';	f
?#	是否相交	select lseg '((-1,0),(1,0))' ?# box '((-2,-2),(2,2))';	t
?-	是否水準對齊	select ?- lseg '((-1,1),(1,1))';	t
?-	兩邊圖形是否水準對齊	select point '(1,0)' ?- point '(0,0)';	t
?|	是否豎直對齊	select ?| lseg '((-1,0),(1,0))';	f
?|	兩邊圖形是否豎直對齊	select point '(0,1)' ?| point '(0,0)';	t
?-|	是否垂直	select lseg '((0,0),(0,1))' ?-| lseg '((0,0),(1,0))';	t
?||	是否平行	select lseg '((-1,0),(1,0))' ?|| lseg '((-1,2),(1,2))';	t
@>	是否包含	select circle '((0,0),2)' @> point '(1,1)';	t
<@	是否包含于或在圖形上	select point '(1,1)' <@ circle '((0,0),2)';	t
~=	是否相同	select polygon '((0,0),(1,1))' ~= polygon '((1,1),(0,0))';	t

函數

函數	傳回值類型	描述	示例	結果
area(object)	double precision	面積	select area(circle'((0,0),1)');	3.14159265358979
center(object)	point	中心	select center(box'(0,0),(1,1)');	(0.5,0.5)
diameter(circle)	double precision	圓周長	select diameter(circle '((0,0),2.0)');	4
height(box)	double precision	矩形豎直高度	select height(box '((0,0),(1,1))');	1
isclosed(path)	boolean	是否為閉合路徑	select isclosed(path '((0,0),(1,1),(2,0))');	t
isopen(path)	boolean	是否為開放路徑	select isopen(path '[(0,0),(1,1),(2,0)]');	t
length(object)	double precision	長度	select length(path '((-1,0),(1,0))');	4
npoints(path)	int	path中的頂點數	select npoints(path '[(0,0),(1,1),(2,0)]');	3
npoints(polygon)	int	多邊形的頂點數	select npoints(polygon '((1,1),(0,0))');	2
pclose(path)	path	将開放path轉換為閉合path	select pclose(path '[(0,0),(1,1),(2,0)]');	((0,0),(1,1),(2,0))
popen(path)	path	将閉合path轉換為開放path	select popen(path '((0,0),(1,1),(2,0))');	[(0,0),(1,1),(2,0)]
radius(circle)	double precision	圓半徑	select radius(circle '((0,0),2.0)');	2
width(box)	double precision	矩形的水準長度	select width(box '((0,0),(1,1))');	1

類型轉換函數

函數	傳回類型	描述	示例	結果
box(circle)	box	圓形轉矩形	select box(circle '((0,0),2.0)');	(1.41421356237309,1.41421356237309),(-1.41421356237309,-1.41421356237309)
box(point)	box	點轉空矩形	select box(point '(0,0)');	(0,0),(0,0)
box(point, point)	box	點轉矩形	select box(point '(0,0)', point '(1,1)');	(1,1),(0,0)
box(polygon)	box	多邊形轉矩形	select box(polygon '((0,0),(1,1),(2,0))');	(2,1),(0,0)
bound_box(box, box)	box	将兩個矩形轉換成一個邊界矩形	select bound_box(box '((0,0),(1,1))', box '((3,3),(4,4))');	(4,4),(0,0)
circle(box)	circle	矩形轉圓形	select circle(box '((0,0),(1,1))');	<(0.5,0.5),0.707106781186548>
circle(point, double precision)	circle	圓心與半徑轉圓形	select circle(point '(0,0)', 2.0);	<(0,0),2>
circle(polygon)	circle	多邊形轉圓形	select circle(polygon '((0,0),(1,1),(2,0))');	<(1,0.333333333333333),0.924950591148529>
line(point, point)	line	點轉直線	select line(point '(-1,0)', point '(1,0)');	{0,-1,0}
lseg(box)	lseg	矩形轉線段	select lseg(box '((-1,0),(1,0))');	[(1,0),(-1,0)]
lseg(point, point)	lseg	點轉線段	select lseg(point '(-1,0)', point '(1,0)');	[(-1,0),(1,0)]
path(polygon)	path	多邊形轉path	select path(polygon '((0,0),(1,1),(2,0))');	((0,0),(1,1),(2,0))
point (double precision, double precision)	point	點	select point(23.4, -44.5);	(23.4,-44.5)
point(box)	point	矩形轉點	select point(box '((-1,0),(1,0))');	(0,0)
point(circle)	point	圓心	select point(circle '((0,0),2.0)');	(0,0)
point(lseg)	point	線段中心	select point(lseg '((-1,0),(1,0))');	(0,0)
point(polygon)	point	多邊形的中心	select point(polygon '((0,0),(1,1),(2,0))');	(1,0.333333333333333)
polygon(box)	polygon	矩形轉4點多邊形	select polygon(box '((0,0),(1,1))');	((0,0),(0,1),(1,1),(1,0))
polygon(circle)	polygon	圓形轉12點多邊形	select polygon(circle '((0,0),2.0)');	((-2,0),(-1.73205080756888,1),(-1,1.73205080756888),(-1.22460635382238e-16,2),(1,1.73205080756888),(1.73205080756888,1),(2,2.4492127 0764475e-16),(1.73205080756888,-0.999999999999999),(1,-1.73205080756888),(3.67381906146713e-16,-2),(-0.999999999999999,-1.73205080756 888),(-1.73205080756888,-1))
polygon(npts, circle)	polygon	圓形轉npts點多邊形	select polygon(12, circle '((0,0),2.0)');	((-2,0),(-1.73205080756888,1),(-1,1.73205080756888),(-1.22460635382238e-16,2),(1,1.73205080756888),(1.73205080756888,1),(2,2.4492127 0764475e-16),(1.73205080756888,-0.999999999999999),(1,-1.73205080756888),(3.67381906146713e-16,-2),(-0.999999999999999,-1.73205080756 888),(-1.73205080756888,-1))
polygon(path)	polygon	将path轉多邊形	select polygon(path '((0,0),(1,1),(2,0))');	((0,0),(1,1),(2,0))