def get_elevation(fixes):
shortener = int(max(1, len(fixes) / 1000))
coordinates = [(fix[2]['longitude'], fix[2]['latitude']) for fix in fixes]
points = MultiPoint(coordinates[::shortener])
locations = from_shape(points, srid=4326).ST_DumpPoints()
locations_id = extract_array_item(locations.path, 1)
subq = db.session.query(locations_id.label('location_id'),
locations.geom.label('location')).subquery()
elevation = Elevation.rast.ST_Value(subq.c.location)
# Prepare main query
q = db.session.query(literal_column('location_id'), elevation.label('elevation')) \
.filter(and_(subq.c.location.ST_Intersects(Elevation.rast),
elevation != None)).all()
fixes_copy = [list(fix) for fix in fixes]
for i in xrange(1, len(q)):
prev = q[i - 1].location_id - 1
current = q[i].location_id - 1
for j in range(prev * shortener, current * shortener):
elev = q[i - 1].elevation + (q[i].elevation - q[i - 1].elevation) * (j - prev * shortener)
fixes_copy[j][11] = elev
return fixes_copy
def get_elevations(flight, encoder):
# Prepare column expressions
locations = Flight.locations.ST_DumpPoints()
location_id = extract_array_item(locations.path, 1)
location = locations.geom
# Prepare subquery
subq = DBSession.query(location_id.label('location_id'),
location.label('location')) \
.filter(Flight.id == flight.id).subquery()
# Prepare column expressions
timestamp = literal_column('timestamps[location_id]')
elevation = Elevation.rast.ST_Value(subq.c.location)
# Prepare main query
q = DBSession.query(timestamp.label('timestamp'),
elevation.label('elevation')) \
.filter(and_(Flight.id == flight.id,
subq.c.location.ST_Intersects(Elevation.rast),
elevation != None)).all()
if len(q) == 0:
return [], []
# Assemble elevation data
elevations_t = []
elevations_h = []
start_time = q[0][0]
start_midnight = start_time.replace(hour=0, minute=0, second=0, microsecond=0)
for time, elevation in q:
time_delta = time - start_midnight
time = time_delta.days * 86400 + time_delta.seconds
elevations_t.append(time)
elevations_h.append(elevation)
# Encode lists
elevations_t = encoder.encodeList(elevations_t)
elevations_h = encoder.encodeList(elevations_h)
return elevations_t, elevations_h
def _get_elevations(flight, encoder):
# Prepare column expressions
locations = Flight.locations.ST_DumpPoints()
location_id = extract_array_item(locations.path, 1)
location = locations.geom
# Prepare subquery
subq = db.session.query(location_id.label('location_id'),
location.label('location')) \
.filter(Flight.id == flight.id).subquery()
# Prepare column expressions
timestamp = literal_column('timestamps[location_id]')
elevation = Elevation.rast.ST_Value(subq.c.location)
# Prepare main query
q = db.session.query(timestamp.label('timestamp'),
elevation.label('elevation')) \
.filter(and_(Flight.id == flight.id,
subq.c.location.ST_Intersects(Elevation.rast),
elevation != None)).all()
if len(q) == 0:
return [], []
# Assemble elevation data
elevations_t = []
elevations_h = []
start_time = q[0][0]
start_midnight = start_time.replace(hour=0, minute=0, second=0, microsecond=0)
for time, elevation in q:
time_delta = time - start_midnight
time = time_delta.days * 86400 + time_delta.seconds
elevations_t.append(time)
elevations_h.append(elevation)
# Encode lists
elevations_t = encoder.encodeList(elevations_t)
elevations_h = encoder.encodeList(elevations_h)
return elevations_t, elevations_h
