The geometric types point, box, lseg, line, path, polygon, and circle have a large set of native
support functions and operators, shown in Table
6-20, Table
6-21, and Table
6-22.
Table 6-20. Geometric Operators
| Operator |
Description |
Usage |
| + |
Translation |
box '((0,0),(1,1))' + point
'(2.0,0)' |
| - |
Translation |
box '((0,0),(1,1))' - point
'(2.0,0)' |
| * |
Scaling/rotation |
box '((0,0),(1,1))' * point
'(2.0,0)' |
| / |
Scaling/rotation |
box '((0,0),(2,2))' / point
'(2.0,0)' |
| # |
Intersection |
'((1,-1),(-1,1))' #
'((1,1),(-1,-1))' |
| # |
Number of points in path or polygon |
# '((1,0),(0,1),(-1,0))' |
| ## |
Point of closest proximity |
point '(0,0)' ## lseg
'((2,0),(0,2))' |
| && |
Overlaps? |
box '((0,0),(1,1))' && box
'((0,0),(2,2))' |
| &< |
Overlaps to left? |
box '((0,0),(1,1))' &< box
'((0,0),(2,2))' |
| &> |
Overlaps to right? |
box '((0,0),(3,3))' &> box
'((0,0),(2,2))' |
| <-> |
Distance between |
circle '((0,0),1)' <->
circle '((5,0),1)' |
| << |
Left of? |
circle '((0,0),1)' << circle
'((5,0),1)' |
| <^ |
Is below? |
circle '((0,0),1)' <^ circle
'((0,5),1)' |
| >> |
Is right of? |
circle '((5,0),1)' >> circle
'((0,0),1)' |
| >^ |
Is above? |
circle '((0,5),1)' >^ circle
'((0,0),1)' |
| ?# |
Intersects or overlaps |
lseg '((-1,0),(1,0))' ?# box
'((-2,-2),(2,2))' |
| ?- |
Is horizontal? |
point '(1,0)' ?- point '(0,0)' |
| ?-| |
Is perpendicular? |
lseg '((0,0),(0,1))' ?-| lseg
'((0,0),(1,0))' |
| @-@ |
Length or circumference |
@-@ path '((0,0),(1,0))' |
| ?| |
Is vertical? |
point '(0,1)' ?| point '(0,0)' |
| ?|| |
Is parallel? |
lseg '((-1,0),(1,0))' ?|| lseg
'((-1,2),(1,2))' |
| @ |
Contained or on |
point '(1,1)' @ circle '((0,0),2)' |
| @@ |
Center of |
@@ circle '((0,0),10)' |
| ~= |
Same as |
polygon '((0,0),(1,1))' ~= polygon
'((1,1),(0,0))' |
Table 6-21. Geometric Functions
| Function |
Returns |
Description |
Example |
| area(object) |
double precision |
area of item |
area(box '((0,0),(1,1))') |
| box(box, box) |
box |
intersection box |
box(box '((0,0),(1,1))',box
'((0.5,0.5),(2,2))') |
| center(object) |
point |
center of item |
center(box '((0,0),(1,2))') |
| diameter(circle) |
double precision |
diameter of circle |
diameter(circle '((0,0),2.0)') |
| height(box) |
double precision |
vertical size of box |
height(box '((0,0),(1,1))') |
| isclosed(path) |
boolean |
a closed path? |
isclosed(path
'((0,0),(1,1),(2,0))') |
| isopen(path) |
boolean |
an open path? |
isopen(path '[(0,0),(1,1),(2,0)]') |
| length(object) |
double precision |
length of item |
length(path '((-1,0),(1,0))') |
| npoints(path) |
integer |
number of points |
npoints(path
'[(0,0),(1,1),(2,0)]') |
| npoints(polygon) |
integer |
number of points |
npoints(polygon '((1,1),(0,0))') |
| pclose(path) |
path |
convert path to closed |
popen(path '[(0,0),(1,1),(2,0)]') |
| popen(path) |
path |
convert path to open path |
popen(path '((0,0),(1,1),(2,0))') |
| radius(circle) |
double precision |
radius of circle |
radius(circle '((0,0),2.0)') |
| width(box) |
double precision |
horizontal size |
width(box '((0,0),(1,1))') |
Table 6-22. Geometric Type Conversion Functions
| Function |
Returns |
Description |
Example |
| box(circle) |
box |
circle to box |
box(circle '((0,0),2.0)') |
| box(point,
point) |
box |
points to box |
box(point '(0,0)', point '(1,1)') |
| box(polygon) |
box |
polygon to box |
box(polygon '((0,0),(1,1),(2,0))') |
| circle(box) |
circle |
to circle |
circle(box '((0,0),(1,1))') |
| circle(point,
double precision) |
circle |
point to circle |
circle(point '(0,0)', 2.0) |
| lseg(box) |
lseg |
box diagonal to lseg |
lseg(box '((-1,0),(1,0))') |
| lseg(point,
point) |
lseg |
points to lseg |
lseg(point '(-1,0)', point
'(1,0)') |
| path(polygon) |
point |
polygon to path |
path(polygon
'((0,0),(1,1),(2,0))') |
| point(circle) |
point |
center |
point(circle '((0,0),2.0)') |
| point(lseg,
lseg) |
point |
intersection |
point(lseg '((-1,0),(1,0))', lseg
'((-2,-2),(2,2))') |
| point(polygon) |
point |
center |
point(polygon
'((0,0),(1,1),(2,0))') |
| polygon(box) |
polygon |
4-point polygon |
polygon(box '((0,0),(1,1))') |
| polygon(circle) |
polygon |
12-point polygon |
polygon(circle '((0,0),2.0)') |
| polygon(npts, circle) |
polygon |
npts polygon |
polygon(12, circle '((0,0),2.0)') |
| polygon(path) |
polygon |
path to polygon |
polygon(path
'((0,0),(1,1),(2,0))') |
It is possible to access the two component numbers of a point as
though it were an array with subscripts 0, 1. For example, if t.p
is a point column then SELECT p[0] FROM t
retrieves the X coordinate; UPDATE t SET p[1] = ... changes the Y
coordinate. In the same way, a box or an lseg
may be treated as an array of two points.
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