def test_polygonize_thresholds(self):
"""Test polygonize raster using gdal with some thresholds."""
raster_path = test_data_path('hazard', 'jakarta_flood_design.tif')
inside_file_name, inside_layer_name, outside_file_name, \
outside_layer_name = polygonize_thresholds(
raster_path, 0.5)
# Syntactic sugar to ignore unused vars.
_ = inside_layer_name
_ = outside_layer_name
driver = ogr.GetDriverByName('ESRI Shapefile')
data_source = driver.Open(inside_file_name, 0)
layer = data_source.GetLayer()
feature_count = layer.GetFeatureCount()
# print 'inside %s' % (inside_file_name)
self.assertEquals(feature_count, 3)
data_source2 = driver.Open(outside_file_name, 0)
layer2 = data_source2.GetLayer()
feature_count2 = layer2.GetFeatureCount()
# print 'outside %s' % (outside_file_name)
self.assertEquals(feature_count2, 1)
def test_polygonize_thresholds(self):
"""Test polygonize raster using gdal with some thresholds."""
raster_path = standard_data_path('hazard', 'jakarta_flood_design.tif')
inside_file_name, inside_layer_name, outside_file_name, \
outside_layer_name = polygonize_thresholds(
raster_path, 0.5)
# Syntactic sugar to ignore unused vars.
_ = inside_layer_name
_ = outside_layer_name
driver = ogr.GetDriverByName('ESRI Shapefile')
data_source = driver.Open(inside_file_name, 0)
layer = data_source.GetLayer()
feature_count = layer.GetFeatureCount()
# print 'inside %s' % (inside_file_name)
self.assertEquals(feature_count, 3)
data_source2 = driver.Open(outside_file_name, 0)
layer2 = data_source2.GetLayer()
feature_count2 = layer2.GetFeatureCount()
# print 'outside %s' % (outside_file_name)
self.assertEquals(feature_count2, 1)
def polygonize_gdal(
raster,
threshold_min=0.0,
threshold_max=float('inf')):
"""
Function to polygonize raster. Areas (pixels) with threshold_min <
pixel_values < threshold_max will be converted to polygons.
:param raster: Raster layer
:type raster: QgsRasterLayer
:param threshold_min: Value that splits raster to flooded or not flooded.
:type threshold_min: float
:param threshold_max: Value that splits raster to flooded or not flooded.
:type threshold_max: float
:returns: Polygonal geometry
:rtype: QgsGeometry
"""
# save qgis raster to disk
base_name = unique_filename()
file_name = base_name + '.tif'
file_writer = QgsRasterFileWriter(file_name)
pipe = QgsRasterPipe()
provider = raster.dataProvider()
if not pipe.set(provider.clone()):
msg = "Cannot set pipe provider"
raise GetDataError(msg)
file_writer.writeRaster(
pipe,
provider.xSize(),
provider.ySize(),
provider.extent(),
provider.crs())
(
inside_file_name,
inside_layer_name,
outside_file_name,
outside_layer_name
) = polygonize_thresholds(file_name, threshold_min, threshold_max)
inside_layer = \
QgsVectorLayer(inside_file_name, inside_layer_name, 'ogr')
outside_layer = \
QgsVectorLayer(outside_file_name, outside_layer_name, 'ogr')
if inside_layer.featureCount() == 0:
return None, None
else:
return inside_layer, outside_layer
def polygonize_gdal(
raster,
threshold_min=0.0,
threshold_max=float('inf')):
"""
Function to polygonize raster. Areas (pixels) with threshold_min <
pixel_values < threshold_max will be converted to polygons.
:param raster: Raster layer
:type raster: QgsRasterLayer
:param threshold_min: Value that splits raster to flooded or not flooded.
:type threshold_min: float
:param threshold_max: Value that splits raster to flooded or not flooded.
:type threshold_max: float
:returns: Polygonal geometry
:rtype: QgsGeometry
"""
# save qgis raster to disk
base_name = unique_filename()
file_name = base_name + '.tif'
file_writer = QgsRasterFileWriter(file_name)
pipe = QgsRasterPipe()
provider = raster.dataProvider()
if not pipe.set(provider.clone()):
msg = "Cannot set pipe provider"
raise GetDataError(msg)
file_writer.writeRaster(
pipe,
provider.xSize(),
provider.ySize(),
provider.extent(),
provider.crs())
(
inside_file_name,
inside_layer_name,
outside_file_name,
outside_layer_name
) = polygonize_thresholds(file_name, threshold_min, threshold_max)
inside_layer = \
QgsVectorLayer(inside_file_name, inside_layer_name, 'ogr')
outside_layer = \
QgsVectorLayer(outside_file_name, outside_layer_name, 'ogr')
if inside_layer.featureCount() == 0:
return None, None
else:
return inside_layer, outside_layer
def test_split_by_polygon_in_out(self):
"""Test split_by_polygon in-out work"""
raster_name = test_data_path(
'hazard',
'jakarta_flood_design.tif')
exposure_name = test_data_path(
'exposure',
'roads_osm_4326.shp')
qgis_exposure = QgsVectorLayer(
exposure_name,
'EXPOSURE',
'ogr')
inside_file_name, inside_layer_name, outside_file_name, \
outside_layer_name = polygonize_thresholds(raster_name, 0.1)
polygon_in = \
QgsVectorLayer(inside_file_name, inside_layer_name, 'ogr')
polygon_out = \
QgsVectorLayer(outside_file_name, outside_layer_name, 'ogr')
layer = split_by_polygon_in_out(
qgis_exposure, polygon_in, polygon_out, 'flooded', 1)
feature_count = layer.featureCount()
self.assertEqual(feature_count, 184)
flooded = 0
iterator = layer.getFeatures()
for feature in iterator:
attributes = feature.attributes()
if attributes[3] == 1:
flooded += 1
self.assertEqual(flooded, 25)
def test_split_by_polygon_in_out(self):
"""Test split_by_polygon in-out work"""
raster_name = test_data_path(
'hazard',
'jakarta_flood_design.tif')
exposure_name = test_data_path(
'exposure',
'roads_osm_4326.shp')
qgis_exposure = QgsVectorLayer(
exposure_name,
'EXPOSURE',
'ogr')
inside_file_name, inside_layer_name, outside_file_name, \
outside_layer_name = polygonize_thresholds(raster_name, 0.1)
polygon_in = \
QgsVectorLayer(inside_file_name, inside_layer_name, 'ogr')
polygon_out = \
QgsVectorLayer(outside_file_name, outside_layer_name, 'ogr')
layer = split_by_polygon_in_out(
qgis_exposure, polygon_in, polygon_out, 'flooded', 1)
feature_count = layer.featureCount()
self.assertEqual(feature_count, 184)
flooded = 0
iterator = layer.getFeatures()
for feature in iterator:
attributes = feature.attributes()
if attributes[3] == 1:
flooded += 1
self.assertEqual(flooded, 25)
