def test_Raster(self):
if not postgis_version.startswith('2.'):
raise SkipTest
from geoalchemy2 import WKTElement, RasterElement
polygon = WKTElement('POLYGON((0 0,1 1,0 1,0 0))', srid=4326)
o = Ocean(polygon.ST_AsRaster(5, 5))
session.add(o)
session.flush()
session.expire(o)
ok_(isinstance(o.rast, RasterElement))
height = session.execute(o.rast.ST_Height()).scalar()
eq_(height, 5)
width = session.execute(o.rast.ST_Width()).scalar()
eq_(width, 5)
# The top left corner is covered by the polygon
top_left_point = WKTElement('Point(0 1)', srid=4326)
top_left = session.execute(o.rast.ST_Value(top_left_point)).scalar()
eq_(top_left, 1)
# The bottom right corner has NODATA
bottom_right_point = WKTElement('Point(1 0)', srid=4326)
bottom_right = session.execute(
o.rast.ST_Value(bottom_right_point)).scalar()
eq_(bottom_right, None)
def test_st_summary_stats_agg(self):
# Create a new raster
polygon = WKTElement('POLYGON((0 0,1 1,0 1,0 0))', srid=4326)
o = Ocean(polygon.ST_AsRaster(5, 6))
session.add(o)
session.flush()
# Define the query to compute stats
stats_agg = select([
func.ST_SummaryStatsAgg(Ocean.__table__.c.rast, 1, True,
1).label("stats")
])
stats_agg_alias = stats_agg.alias("stats_agg")
# Use these stats
query = select([
stats_agg_alias.c.stats.count.label("count"),
stats_agg_alias.c.stats.sum.label("sum"),
stats_agg_alias.c.stats.stddev.label("stddev"),
stats_agg_alias.c.stats.min.label("min"),
stats_agg_alias.c.stats.max.label("max")
])
# Check the query
assert str(query) == (
"SELECT "
"(stats_agg.stats).count AS count, "
"(stats_agg.stats).sum AS sum, "
"(stats_agg.stats).stddev AS stddev, "
"(stats_agg.stats).min AS min, "
"(stats_agg.stats).max AS max \n"
"FROM ("
"SELECT "
"ST_SummaryStatsAgg("
"public.ocean.rast, "
"%(ST_SummaryStatsAgg_1)s, %(ST_SummaryStatsAgg_2)s, %(ST_SummaryStatsAgg_3)s"
") AS stats \n"
"FROM public.ocean) AS stats_agg")
# Execute the query
res = session.execute(query).fetchall()
# Check the result
assert res == [(15, 15.0, 0.0, 1.0, 1.0)]
def test_decipher_raster(self, pixel_type):
"""Create a raster and decipher it"""
# Create a new raster
polygon = WKTElement('POLYGON((0 0,1 1,0 1,0 0))', srid=4326)
o = Ocean(polygon.ST_AsRaster(5, 6, pixel_type))
session.add(o)
session.flush()
# Decipher data from each raster
image = wkbImage(o.rast.data)
# Define expected result
expected = [[0, 1, 1, 1, 1], [1, 1, 1, 1, 1], [0, 1, 1, 1, 0],
[0, 1, 1, 0, 0], [0, 1, 0, 0, 0], [0, 0, 0, 0, 0]]
# Check results
band = image[0]
assert band == expected