Is there a PostGIS function for checking the validity of a lon/lat pair, given a coordinate system?

Question

I have data with lon lat pairs that I'm converting to geography types. Some of the pairs, however, are corrupt -- in my case, very negative values for longitude.

Is there a helper function in postgis that I can use to exclude such pairs? I'd like to exclude rows whose lon lat values aren't valid given the range of my coordinate system.

I'd like to do something like:

select *
from data_with_lonlats
where POINT_IS_VALID(ST_POINT(longitude, latitude), 4326)

where 4326 is my coordinate system, which has range [-180 -90, 180 90].

Answer 1

Here's a function to do this:

CREATE OR REPLACE FUNCTION is_valid_geography(geometry) RETURNS boolean AS
  'SELECT ST_XMin($1) >= -180 AND ST_XMax($1) <= 180 AND
          ST_YMin($1) >= -90 AND ST_YMax($1) <= 90;'
  LANGUAGE sql IMMUTABLE STRICT;

It should work on any type of geometry.