def read_from_file(self, filename):
# Open data file for reading
# File must be kept open, otherwise GDAL methods segfault.
fid = self.fid = gdal.Open(filename, gdal.GA_ReadOnly)
if fid is None:
msg = 'Could not open file %s' % filename
raise Exception(msg)
# Record raster metadata from file
basename, ext = os.path.splitext(filename)
# If file is ASCII, check that projection is around.
# GDAL does not check this nicely, so it is worth an
# error message
if ext == '.asc':
try:
open(basename + '.prj')
except IOError:
msg = ('Projection file not found for %s. You must supply '
'a projection file with extension .prj' % filename)
raise RuntimeError(msg)
# Look for any keywords
self.keywords = read_keywords(basename + '.keywords')
# Determine name
if 'title' in self.keywords:
rastername = self.keywords['title']
else:
# Use basename without leading directories as name
rastername = os.path.split(basename)[-1]
self.name = rastername
self.filename = filename
self.projection = Projection(self.fid.GetProjection())
self.geotransform = self.fid.GetGeoTransform()
self.columns = fid.RasterXSize
self.rows = fid.RasterYSize
self.number_of_bands = fid.RasterCount
# Assume that file contains all data in one band
msg = 'Only one raster band currently allowed'
if self.number_of_bands > 1:
msg = ('WARNING: Number of bands in %s are %i. '
'Only the first band will currently be '
'used.' % (filename, self.number_of_bands))
# FIXME(Ole): Let us use python warnings here
raise Exception(msg)
# Get first band.
band = self.band = fid.GetRasterBand(1)
if band is None:
msg = 'Could not read raster band from %s' % filename
raise Exception(msg)
def test_keywords_file(self):
"""Keywords can be written and read
"""
kwd_filename = unique_filename(suffix='.keywords')
keywords = {'caption': 'Describing the layer',
'category': 'impact',
'subcategory': 'flood',
'layer': None,
'with spaces': 'trailing_ws '}
write_keywords(keywords, kwd_filename)
msg = 'Keywords file %s was not created' % kwd_filename
assert os.path.isfile(kwd_filename), msg
x = read_keywords(kwd_filename)
os.remove(kwd_filename)
assert isinstance(x, dict)
# Check keyword names
for key in x:
msg = 'Read unexpected key %s' % key
assert key in keywords, msg
for key in keywords:
msg = 'Expected key %s was not read from %s' % (key,
kwd_filename)
assert key in x, msg
# Check keyword values
for key in keywords:
refval = keywords[key]
newval = x[key]
if refval is None:
assert newval is None
else:
msg = ('Expected value %s was not read from %s. '
'I got %s' % (refval, kwd_filename, newval))
assert refval.strip() == newval, msg
# Check catching of wrong extension
kwd_filename = unique_filename(suffix='.xxxx')
try:
write_keywords(keywords, kwd_filename)
except:
pass
else:
msg = 'Should have raised assertion error for wrong extension'
raise Exception(msg)
def test_empty_keywords_file(self):
"""Empty keywords can be handled
"""
kwd_filename = unique_filename(suffix='.keywords')
write_keywords({}, kwd_filename)
msg = 'Keywords file %s was not created' % kwd_filename
assert os.path.isfile(kwd_filename), msg
x = read_keywords(kwd_filename)
os.remove(kwd_filename)
assert isinstance(x, dict)
assert len(x) == 0
def read_from_file(self, filename):
""" Read and unpack vector data.
It is assumed that the file contains only one layer with the
pertinent features. Further it is assumed for the moment that
all geometries are points.
* A feature is a geometry and a set of attributes.
* A geometry refers to location and can be point, line, polygon or
combinations thereof.
* The attributes or obtained through GetField()
The full OGR architecture is documented at
* http://www.gdal.org/ogr/ogr_arch.html
* http://www.gdal.org/ogr/ogr_apitut.html
Examples are at
* danieljlewis.org/files/2010/09/basicpythonmap.pdf
* http://invisibleroads.com/tutorials/gdal-shapefile-points-save.html
* http://www.packtpub.com/article/geospatial-data-python-geometry
"""
basename, _ = os.path.splitext(filename)
# Look for any keywords
self.keywords = read_keywords(basename + ".keywords")
# Determine name
if "title" in self.keywords:
vectorname = self.keywords["title"]
else:
# Use basename without leading directories as name
vectorname = os.path.split(basename)[-1]
self.name = vectorname
self.filename = filename
self.geometry_type = None # In case there are no features
fid = ogr.Open(filename)
if fid is None:
msg = "Could not open %s" % filename
raise IOError(msg)
# Assume that file contains all data in one layer
msg = "Only one vector layer currently allowed"
if fid.GetLayerCount() > 1:
msg = (
"WARNING: Number of layers in %s are %i. "
"Only the first layer will currently be "
"used." % (filename, fid.GetLayerCount())
)
raise Exception(msg)
layer = fid.GetLayerByIndex(0)
# Get spatial extent
self.extent = layer.GetExtent()
# Get projection
p = layer.GetSpatialRef()
self.projection = Projection(p)
# Get number of features
N = layer.GetFeatureCount()
# Extract coordinates and attributes for all features
geometry = []
data = []
for i in range(N):
feature = layer.GetFeature(i)
if feature is None:
msg = "Could not get feature %i from %s" % (i, filename)
raise Exception(msg)
# Record coordinates ordered as Longitude, Latitude
G = feature.GetGeometryRef()
if G is None:
msg = "Geometry was None in filename %s " % filename
raise Exception(msg)
else:
self.geometry_type = G.GetGeometryType()
if self.geometry_type == ogr.wkbPoint:
geometry.append((G.GetX(), G.GetY()))
elif self.geometry_type == ogr.wkbPolygon:
ring = G.GetGeometryRef(0)
M = ring.GetPointCount()
coordinates = []
for j in range(M):
coordinates.append((ring.GetX(j), ring.GetY(j)))
# Record entire polygon ring as an Mx2 numpy array
geometry.append(numpy.array(coordinates, dtype="d", copy=False))
else:
msg = (
"Only point and polygon geometries are supported. "
"Geometry in filename %s "
"was %s." % (filename, G.GetGeometryType())
)
raise Exception(msg)
# Record attributes by name
number_of_fields = feature.GetFieldCount()
fields = {}
for j in range(number_of_fields):
name = feature.GetFieldDefnRef(j).GetName()
# FIXME (Ole): Ascertain the type of each field?
# We need to cast each appropriately?
# This is issue #66
# feature_type = feature.GetFieldDefnRef(j).GetType()
fields[name] = feature.GetField(j)
# print 'Field', name, feature_type, j, fields[name]
data.append(fields)
# Store geometry coordinates as a compact numeric array
self.geometry = geometry
self.data = data
def read_from_file(self, filename):
""" Read and unpack vector data.
It is assumed that the file contains only one layer with the
pertinent features. Further it is assumed for the moment that
all geometries are points.
* A feature is a geometry and a set of attributes.
* A geometry refers to location and can be point, line, polygon or
combinations thereof.
* The attributes or obtained through GetField()
The full OGR architecture is documented at
* http://www.gdal.org/ogr/ogr_arch.html
* http://www.gdal.org/ogr/ogr_apitut.html
Examples are at
* danieljlewis.org/files/2010/09/basicpythonmap.pdf
* http://invisibleroads.com/tutorials/gdal-shapefile-points-save.html
* http://www.packtpub.com/article/geospatial-data-python-geometry
"""
basename, _ = os.path.splitext(filename)
# Look for any keywords
self.keywords = read_keywords(basename + '.keywords')
# Determine name
if 'title' in self.keywords:
vectorname = self.keywords['title']
else:
# Use basename without leading directories as name
vectorname = os.path.split(basename)[-1]
self.name = vectorname
self.filename = filename
self.geometry_type = None # In case there are no features
fid = ogr.Open(filename)
if fid is None:
msg = 'Could not open %s' % filename
raise IOError(msg)
# Assume that file contains all data in one layer
msg = 'Only one vector layer currently allowed'
if fid.GetLayerCount() > 1:
msg = ('WARNING: Number of layers in %s are %i. '
'Only the first layer will currently be '
'used.' % (filename, fid.GetLayerCount()))
raise Exception(msg)
layer = fid.GetLayerByIndex(0)
# Get spatial extent
self.extent = layer.GetExtent()
# Get projection
p = layer.GetSpatialRef()
self.projection = Projection(p)
# Get number of features
N = layer.GetFeatureCount()
# Extract coordinates and attributes for all features
geometry = []
data = []
for i in range(N):
feature = layer.GetFeature(i)
if feature is None:
msg = 'Could not get feature %i from %s' % (i, filename)
raise Exception(msg)
# Record coordinates ordered as Longitude, Latitude
G = feature.GetGeometryRef()
if G is None:
msg = ('Geometry was None in filename %s ' % filename)
raise Exception(msg)
else:
self.geometry_type = G.GetGeometryType()
if self.geometry_type == ogr.wkbPoint:
geometry.append((G.GetX(), G.GetY()))
elif self.geometry_type == ogr.wkbPolygon:
ring = G.GetGeometryRef(0)
M = ring.GetPointCount()
coordinates = []
for j in range(M):
coordinates.append((ring.GetX(j), ring.GetY(j)))
# Record entire polygon ring as an Mx2 numpy array
geometry.append(
numpy.array(coordinates, dtype='d', copy=False))
else:
msg = ('Only point and polygon geometries are supported. '
'Geometry in filename %s '
'was %s.' % (filename, G.GetGeometryType()))
raise Exception(msg)
# Record attributes by name
number_of_fields = feature.GetFieldCount()
fields = {}
for j in range(number_of_fields):
name = feature.GetFieldDefnRef(j).GetName()
# FIXME (Ole): Ascertain the type of each field?
# We need to cast each appropriately?
# This is issue #66
#feature_type = feature.GetFieldDefnRef(j).GetType()
fields[name] = feature.GetField(j)
#print 'Field', name, feature_type, j, fields[name]
data.append(fields)
# Store geometry coordinates as a compact numeric array
self.geometry = geometry
self.data = data