Module: PostgisFunctions::PointFunctions

Defined in:
lib/postgis_functions/common.rb

Overview

POINT

Instance Method Summary collapse

Instance Method Details

#azimuth(other) ⇒ Object

The azimuth of the segment defined by the given Point geometries, or NULL if the two points are coincident. Return value is in radians.

The Azimuth is mathematical concept defined as the angle, in this case measured in radian, between a reference plane and a point.

Returns Float ST_Azimuth(geometry pointA, geometry pointB);



795
796
797
798
799
800
 
# File 'lib/postgis_functions/common.rb', line 795

def azimuth other
  #TODO: return if not point/point
  postgis_calculate(:azimuth, [self, other]).to_f
  rescue
    ActiveRecord::StatementInvalid
end

#distance_sphere_to(other) ⇒ Object

Linear distance in meters between two lon/lat points. Uses a spherical earth and radius of 6370986 meters. Faster than ‘distance_spheroid’, but less accurate.

Only implemented for points.

Returns Float ST_Distance_Sphere(geometry pointlonlatA, geometry pointlonlatB);



759
760
761
 
# File 'lib/postgis_functions/common.rb', line 759

def distance_sphere_to(other)
  postgis_calculate(:distance_sphere, [self, other]).to_f
end

#distance_spheroid_to(other, spheroid = EARTH_SPHEROID) ⇒ Object

Calculates the distance on an ellipsoid. This is useful if the coordinates of the geometry are in longitude/latitude and a length is desired without reprojection. The ellipsoid is a separate database type and can be constructed as follows:

This is slower then ‘distance_sphere_to’, but more precise.

SPHEROID[<NAME>,<SEMI-MAJOR AXIS>,<INVERSE FLATTENING>]

Example:

SPHEROID["GRS_1980",6378137,298.257222101]

Defaults to:

SPHEROID["IERS_2003",6378136.6,298.25642]

Returns ST_Distance_Spheroid(geometry geomA, geometry geomB, spheroid);



782
783
784
 
# File 'lib/postgis_functions/common.rb', line 782

def distance_spheroid_to(other, spheroid = EARTH_SPHEROID)
  postgis_calculate(:distance_spheroid, [self, other], spheroid).to_f
end

#inside_circle?(x, y, r) ⇒ Boolean

True if the geometry is a point and is inside the circle.

Returns Boolean ST_point_inside_circle(geometry, float, float, float)

Returns:

  • (Boolean) 


807
808
809
 
# File 'lib/postgis_functions/common.rb', line 807

def inside_circle?(x,y,r)
  postgis_calculate(:point_inside_circle, self, [x,y,r])
end

#where_on_line(line) ⇒ Object

Returns a float between 0 and 1 representing the location of the closest point on LineString to the given Point, as a fraction of total 2d line length.

You can use the returned location to extract a Point (ST_Line_Interpolate_Point) or a substring (ST_Line_Substring).

This is useful for approximating numbers of addresses.

Returns float (0 to 1) ST_Line_Locate_Point(geometry a_linestring, geometry a_point);



746
747
748
 
# File 'lib/postgis_functions/common.rb', line 746

def where_on_line line
  postgis_calculate(:line_locate_point, [line, self]).to_f
end