def nearest_qmed_catchments(self, subject_catchment, limit=None, dist_limit=500):
dist_sq = Catchment.distance_to(subject_catchment).label('dist_sq') # Distance squared, calculated using SQL
query = self.db_session.query(Catchment, dist_sq). \
join(Catchment.descriptors). \
filter(Catchment.id != subject_catchment.id, # Exclude subject catchment itself
Catchment.id.in_(self.catchment_ids),
Catchment.country == subject_catchment.country, # SQL dist method does not cover cross-boundary dist
# Within the distance limit
dist_sq <= dist_limit ** 2). \
group_by(Catchment). \
order_by(dist_sq)
if limit:
rows = query[0:limit] # Each row is tuple of (catchment, distance squared)
else:
rows = query.all()
# Add real `dist` attribute to catchment list using previously calculated SQL dist squared
catchments = []
for row in rows:
catchment = row[0]
catchment.dist = sqrt(row[1])
catchments.append(catchment)
return catchments
def nearest_qmed_catchments(self,
subject_catchment,
limit=None,
dist_limit=500):
dist_sq = Catchment.distance_to(subject_catchment).label(
'dist_sq') # Distance squared, calculated using SQL
query = self.db_session.query(Catchment, dist_sq). \
join(Catchment.descriptors). \
filter(Catchment.id != subject_catchment.id, # Exclude subject catchment itself
Catchment.id.in_(self.catchment_ids),
Catchment.country == subject_catchment.country, # SQL dist method does not cover cross-boundary dist
# Within the distance limit
dist_sq <= dist_limit ** 2). \
group_by(Catchment). \
order_by(dist_sq)
if limit:
rows = query[
0:limit] # Each row is tuple of (catchment, distance squared)
else:
rows = query.all()
# Add real `dist` attribute to catchment list using previously calculated SQL dist squared
catchments = []
for row in rows:
catchment = row[0]
catchment.dist = sqrt(row[1])
catchments.append(catchment)
return catchments
def test_catchment_distance_no_country(self):
catchment_1 = Catchment("Aberdeen", "River Dee")
catchment_1.descriptors.centroid_ngr = Point(0, 0)
catchment_2 = Catchment("Dundee", "River Tay")
catchment_2.descriptors.centroid_ngr = Point(3000, 4000)
self.assertEqual(catchment_1.distance_to(catchment_2), 5)
def test_catchment_distance_no_country(self):
catchment_1 = Catchment("Aberdeen", "River Dee")
catchment_1.descriptors.centroid_ngr = Point(0, 0)
catchment_2 = Catchment("Dundee", "River Tay")
catchment_2.descriptors.centroid_ngr = Point(3000, 4000)
self.assertEqual(catchment_1.distance_to(catchment_2), 5)
def test_catchment_distance_different_country(self):
catchment_1 = Catchment("Aberdeen", "River Dee")
catchment_1.descriptors.centroid_ngr = Point(0, 0)
catchment_2 = Catchment("Belfast")
catchment_2.descriptors.centroid_ngr = Point(3, 4)
catchment_2.country = 'ni'
self.assertEqual(catchment_1.distance_to(catchment_2), float('inf'))
def test_catchment_distance_different_country(self):
catchment_1 = Catchment("Aberdeen", "River Dee")
catchment_1.descriptors.centroid_ngr = Point(0, 0)
catchment_2 = Catchment("Belfast")
catchment_2.descriptors.centroid_ngr = Point(3, 4)
catchment_2.country = 'ni'
self.assertEqual(catchment_1.distance_to(catchment_2), float('inf'))