def _within_distance(compiler, geom1, geom2, distance, *args):
"""MySQL does not support the function distance, so we are doing
a kind of "mbr_within_distance". The MBR of 'geom2' is expanded with
the amount of 'distance' by manually changing the coordinates.
Then we test if 'geom1' intersects this expanded MBR.
"""
mbr = func.ExteriorRing(func.Envelope(geom2))
lower_left = func.StartPoint(mbr)
upper_right = func.PointN(mbr, 3)
xmin = func.X(lower_left)
ymin = func.Y(lower_left)
xmax = func.X(upper_right)
ymax = func.Y(upper_right)
return func.Intersects(
geom1,
func.GeomFromText(
func.Concat('Polygon((', xmin - distance, ' ', ymin - distance,
',', xmax + distance, ' ', ymin - distance, ',',
xmax + distance, ' ', ymax + distance, ',',
xmin - distance, ' ', ymax + distance, ',',
xmin - distance, ' ', ymin - distance, '))'),
func.srid(geom2)))
def test_centroid(self):
l = session.query(Lake).get(1)
r = session.query(Road).get(1)
s = session.query(Spot).get(1)
assert_almost_equal(session.scalar(func.X(l.lake_geom.centroid)),
-88.7578400578)
assert_almost_equal(session.scalar(func.Y(l.lake_geom.centroid)),
43.1937975407)
#eq_(b2a_hex(session.scalar(l.lake_geom.centroid)), '0001ffffffff81ec9573803056c04bc4995bce98454081ec9573803056c04bc4995bce9845407c0100000081ec9573803056c04bc4995bce984540fe')
assert_almost_equal(session.scalar(func.X(r.road_geom.centroid)),
-88.6569666079)
assert_almost_equal(session.scalar(func.Y(r.road_geom.centroid)),
42.8422057576)
#eq_(b2a_hex(session.scalar(r.road_geom.centroid)), '0001ffffffff1cecabbd0b2a56c022b0f465cd6b45401cecabbd0b2a56c022b0f465cd6b45407c010000001cecabbd0b2a56c022b0f465cd6b4540fe')
assert_almost_equal(session.scalar(func.X(s.spot_location.centroid)),
-88.5945861592)
assert_almost_equal(session.scalar(func.Y(s.spot_location.centroid)),
42.9480095987)
def test_end_point(self):
l = session.query(Lake).get(1)
r = session.query(Road).get(1)
s = session.query(Spot).get(1)
ok_(not session.scalar(l.lake_geom.end_point))
assert_almost_equal(session.scalar(func.X(r.road_geom.end_point)),
-88.3655256496815)
assert_almost_equal(session.scalar(func.Y(r.road_geom.end_point)),
43.1402866687898)
#eq_(b2a_hex(session.scalar(r.road_geom.end_point)), '0001ffffffffccceb1c5641756c02c42dfe9f4914540ccceb1c5641756c02c42dfe9f49145407c01000000ccceb1c5641756c02c42dfe9f4914540fe')
ok_(not session.scalar(s.spot_location.end_point))
def test_start_point(self):
l = session.query(Lake).get(1)
r = session.query(Road).get(1)
s = session.query(Spot).get(1)
ok_(not session.scalar(l.lake_geom.start_point))
assert_almost_equal(session.scalar(func.X(r.road_geom.start_point)),
-88.9139332929936)
assert_almost_equal(session.scalar(func.Y(r.road_geom.start_point)),
42.5082802993631)
#eq_(b2a_hex(session.scalar(r.road_geom.start_point)), '0001ffffffff850811e27d3a56c0997b2f540f414540850811e27d3a56c0997b2f540f4145407c01000000850811e27d3a56c0997b2f540f414540fe')
ok_(not session.scalar(s.spot_location.start_point))
