Changes between Initial Version and Version 1 of UsersWikiCardinalDirection


Ignore:
Timestamp:
Oct 26, 2011 7:17:04 PM (4 years ago)
Author:
mwtoews
Comment:

contribute

Legend:

Unmodified
Added
Removed
Modified
  • UsersWikiCardinalDirection

    v1 v1  
     1= Determine Cardinal Direction =
     2
     3See [http://en.wikipedia.org/wiki/Cardinal_direction Wikipedia] for a description for cardinal direction.
     4
     5{{{
     6-- Function: ST_Cardinal_Direction(azimuth float8)
     7-- Returns N, NW, W, SW, S, SE, E, or NE from an azimuth direction
     8-- By: Mike Toews
     9--
     10-- Usage:
     11-- postgis=# SELECT ST_Cardinal_Direction(
     12-- postgis(#          ST_Azimuth('POINT(3 5)', 'POINT(5 5)'));
     13--  st_cardinal_direction
     14-- -----------------------
     15--  E
     16-- (1 row)
     17--
     18-- DROP FUNCTION ST_Cardinal_Direction(float8);
     19
     20CREATE OR REPLACE FUNCTION ST_Cardinal_Direction(azimuth float8)
     21  RETURNS character varying AS
     22$BODY$SELECT CASE
     23WHEN $1 < 0.0 THEN 'less than 0'
     24WHEN $1*180/pi() < 22.5 THEN 'N'
     25WHEN $1*180/pi() < 67.5 THEN 'NE'
     26WHEN $1*180/pi() < 112.5 THEN 'E'
     27WHEN $1*180/pi() < 157.5 THEN 'SE'
     28WHEN $1*180/pi() < 202.5 THEN 'S'
     29WHEN $1*180/pi() < 247.5 THEN 'SW'
     30WHEN $1*180/pi() < 292.5 THEN 'W'
     31WHEN $1*180/pi() < 337.5 THEN 'NW'
     32WHEN $1*180/pi() <= 360.0 THEN 'N'
     33END;$BODY$ LANGUAGE sql IMMUTABLE COST 100;
     34COMMENT ON FUNCTION ST_Cardinal_Direction(float8) IS 'input azimuth in radians; returns N, NW, W, SW, S, SE, E, or NE';
     35}}}