6.7. spath functions

6.7. `spath` functions
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6.7. `spath` functions #

6.7.1. Count of points
6.7.2. Positions at a path

6.7.1. Count of points #

You can get the count of points of a spherical path using the function:

npoints( path);

spath path;

Example 6.13. Count of spath's points

sql> SELECT npoints ( spath '{(0,0),(1,0)}' );
 npoints
---------
       2
 (1 row)

6.7.2. Positions at a path #

pgSphere provides three functions to get points at a path.

`spoint(`	`path`,
	`i)`;

spath path;
int4 i;

`spoint(`	`path`,
	`f)`;

spath path;
float8 f;

spath_as_array( path);

spath path;

The first function returns the i-th point of a path. If i is less than 1 or larger than the count of spath points, the function returns NULL. The second function does nearly the same, but does linear interpolation between edge positions.

Example 6.14. Get the “center” of a one segment spath

sql> SELECT spoint ( spath '{(0d,0d),(30d,0d)}', 1.5 );
  spoint
------------
 (15d , 0d)
(1 row)

Example 6.15. Get i-th point of a path

sql> SELECT spoint( spath '{(0, 0),(1, 1)}', 1 );
   spoint  
------------
  (0 , 0) 
(1 row)

sql> SELECT spoint( spath '{(0, 0),(1, 1)}', 2 );
   spoint  
------------
  (1 , 1) 
(1 row)

Example 6.16. Get array representation of points

sql> SELECT spath_as_array( spath '{(0, 0),(1, 1)}');
    spath_as_array     
-----------------------
 {"(0 , 0)","(1 , 1)"}
(1 row)