The geometric types point
, box
,
lseg
, line
, path
,
polygon
, and circle
have a large set of
native support functions and operators, shown in Table 9.28, “Geometric Operators”, Table 9.29, “Geometric Functions”, and Table 9.30, “Geometric Type Conversion Functions”.
Table 9.28. Geometric Operators
Operator | Description | Example |
---|---|---|
+ |
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)' |
# |
Point or box of intersection | '((1,-1),(-1,1))' # '((1,1),(-1,-1))' |
# |
Number of points in path or polygon | # '((1,0),(0,1),(-1,0))' |
@-@ |
Length or circumference | @-@ path '((0,0),(1,0))' |
@@ |
Center | @@ circle '((0,0),10)' |
## |
Closest point to first operand on second operand | point '(0,0)' ## lseg '((2,0),(0,2))' |
<-> |
Distance between | circle '((0,0),1)' <-> circle '((5,0),1)' |
&& |
Overlaps? | box '((0,0),(1,1))' && box '((0,0),(2,2))' |
&< |
Does not extend to the right of? | box '((0,0),(1,1))' &< box '((0,0),(2,2))' |
&> |
Does not extend to the left of? | box '((0,0),(3,3))' &> box '((0,0),(2,2))' |
<< |
Is left of? | circle '((0,0),1)' << circle '((5,0),1)' |
>> |
Is right of? | circle '((5,0),1)' >> circle '((0,0),1)' |
<^ |
Is below? | circle '((0,0),1)' <^ circle '((0,5),1)' |
>^ |
Is above? | circle '((0,5),1)' >^ circle '((0,0),1)' |
?# |
Intersects? | lseg '((-1,0),(1,0))' ?# box '((-2,-2),(2,2))' |
?- |
Is horizontal? | ?- lseg '((-1,0),(1,0))' |
?- |
Are horizontally aligned? | point '(1,0)' ?- point '(0,0)' |
?| |
Is vertical? | ?| lseg '((-1,0),(1,0))' |
?| |
Are vertically aligned? | point '(0,1)' ?| point '(0,0)' |
?-| |
Is perpendicular? | lseg '((0,0),(0,1))' ?-| lseg '((0,0),(1,0))' |
?|| |
Are parallel? | lseg '((-1,0),(1,0))' ?|| lseg '((-1,2),(1,2))' |
~ |
Contains? | circle '((0,0),2)' ~ point '(1,1)' |
@ |
Contained in or on? | point '(1,1)' @ circle '((0,0),2)' |
~= |
Same as? | polygon '((0,0),(1,1))' ~= polygon '((1,1),(0,0))' |
Table 9.29. Geometric Functions
Function | Return Type | Description | Example |
---|---|---|---|
|
double precision |
area | area(box '((0,0),(1,1))') |
|
box |
intersection box | box_intersect(box '((0,0),(1,1))',box '((0.5,0.5),(2,2))') |
|
point |
center | center(box '((0,0),(1,2))') |
|
double precision |
diameter of circle | diameter(circle '((0,0),2.0)') |
|
double precision |
vertical size of box | height(box '((0,0),(1,1))') |
|
boolean |
a closed path? | isclosed(path '((0,0),(1,1),(2,0))') |
|
boolean |
an open path? | isopen(path '[(0,0),(1,1),(2,0)]') |
|
double precision |
length | length(path '((-1,0),(1,0))') |
|
integer |
number of points | npoints(path '[(0,0),(1,1),(2,0)]') |
|
integer |
number of points | npoints(polygon '((1,1),(0,0))') |
|
path |
convert path to closed | pclose(path '[(0,0),(1,1),(2,0)]') |
|
path |
convert path to open | popen(path '((0,0),(1,1),(2,0))') |
|
double precision |
radius of circle | radius(circle '((0,0),2.0)') |
|
double precision |
horizontal size of box | width(box '((0,0),(1,1))') |
Table 9.30. Geometric Type Conversion Functions
Function | Return Type | Description | Example |
---|---|---|---|
|
box |
circle to box | box(circle '((0,0),2.0)') |
|
box |
points to box | box(point '(0,0)', point '(1,1)') |
|
box |
polygon to box | box(polygon '((0,0),(1,1),(2,0))') |
|
circle |
box to circle | circle(box '((0,0),(1,1))') |
|
circle |
center and radius to circle | circle(point '(0,0)', 2.0) |
|
lseg |
box diagonal to line segment | lseg(box '((-1,0),(1,0))') |
|
lseg |
points to line segment | lseg(point '(-1,0)', point '(1,0)') |
|
point |
polygon to path | path(polygon '((0,0),(1,1),(2,0))') |
|
point |
construct point | point(23.4, -44.5) |
|
point |
center of box | point(box '((-1,0),(1,0))') |
|
point |
center of circle | point(circle '((0,0),2.0)') |
|
point |
center of lseg | point(lseg '((-1,0),(1,0))') |
|
point |
intersection | point(lseg '((-1,0),(1,0))', lseg '((-2,-2),(2,2))') |
|
point |
center of polygon | point(polygon '((0,0),(1,1),(2,0))') |
|
polygon |
box to 4-point polygon | polygon(box '((0,0),(1,1))') |
|
polygon |
circle to 12-point polygon | polygon(circle '((0,0),2.0)') |
|
polygon |
circle to npts -point polygon |
polygon(12, circle '((0,0),2.0)') |
|
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 indices 0 and 1. For example, if
t.p
is a point
column then
SELECT p[0] FROM t
retrieves the X coordinate and
UPDATE t SET p[1] = ...
changes the Y coordinate.
In the same way, a value of type box
or lseg
may be treated
as an array of two point
values.
The area
function works for the types
box
, circle
, and path
.
The area
function only works on the
path
data type if the points in the
path
are non-intersecting. For example, the
path
'((0,0),(0,1),(2,1),(2,2),(1,2),(1,0),(0,0))'::PATH
won't work, however, the following visually identical
path
'((0,0),(0,1),(1,1),(1,2),(2,2),(2,1),(1,1),(1,0),(0,0))'::PATH
will work. If the concept of an intersecting versus
non-intersecting path
is confusing, draw both of the
above path
s side by side on a piece of graph paper.