4.7. Path
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## 4.7. Path #

Similar to spherical polygons, you can use the aggregate function

`spath(` | edge`)`; |

`spoint edge`;

to create a spherical path using a set of spherical points. There are the same restrictions as with the input function of spherical path (see Section 3.7). The function returns `NULL` if the path couldn't be created.

Example 4.8. Create a spherical path using a set of spherical points

Create a table and put in some spherical points with a unique ID. Then, create a spherical path from it.

    sql> SELECT set_sphere_output('DEG');
     set_sphere_output
    -------------------
     SET DEG
    (1 row)

    sql> CREATE TABLE points ( i int PRIMARY KEY, p spoint );
    sql> INSERT INTO points VALUES (1, '( 0d, 10d)');
    sql> INSERT INTO points VALUES (2, '( 0d,  0d)');
    sql> INSERT INTO points VALUES (3, '( 0d,-10d)');
    sql> SELECT spath(data.p) FROM ( SELECT p FROM points ORDER BY i ASC ) AS data ;
                           spath
    ---------------------------------------------------
     {(0d , 10d),(0d , 0d),(0d , -10d)}
    (1 row)
    sql> SELECT spath(data.p) FROM ( SELECT p FROM points ORDER BY i DESC ) AS data ;
                           spath
    ---------------------------------------------------
     {(0d , -10d),(0d , 0d),(0d , 10d)}
    (1 row)

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