out_feat.SetField('X_default', pt.GetX())
out_feat.SetField('Y_default', pt.GetY())
out_feat.SetField('X_short', pt.GetX())
out_feat.SetField('Y_short', pt.GetY())
out_lyr.CreateFeature(out_feat)
######################## 3.6 Updating existing data #########################
# Set things up for the following examples.
original_fn = os.path.join(data_dir, 'Washington', 'large_cities.shp')
new_fn = os.path.join(data_dir, 'output', 'large_cities2.shp')
# First make a copy of a shapefile so you have something to test things on.
pb.copy_datasource(original_fn, new_fn)
# Open the copied shapefile for writing.
ds = ogr.Open(new_fn, 1)
if ds is None:
sys.exit('Could not open {0}.'.format(new_fn))
lyr = ds.GetLayer(0)
# Take a look at the attributes before you change anything.
print('Original attributes')
pb.print_attributes(lyr, geom=False)
#################### 3.6.1 Changing the layer definition ####################
# Change the name of the "Name" attribute field by creating a new field
######################## 4.3 Testing capabilities ###########################
# Test if you can create a new shapefile in a folder opened for reading only.
dirname = os.path.join(data_dir, 'global')
ds = ogr.Open(dirname)
print(ds.TestCapability(ogr.ODsCCreateLayer))
# Test if you can create a new shapefile in a folder opened for writing.
ds = ogr.Open(dirname, 1)
print(ds.TestCapability(ogr.ODsCCreateLayer))
# Make a copy of a shapefile for the following examples.
original_fn = os.path.join(data_dir, 'Washington', 'large_cities2.shp')
new_fn = os.path.join(data_dir, 'output', 'large_cities3.shp')
pb.copy_datasource(original_fn, new_fn)
# Try opening the datasource read-only and see if you can add a field (you
# can't). The example in the book opens it for writing, as in the next
# snippet in this file).
ds = ogr.Open(new_fn, 0)
if ds is None:
sys.exit('Could not open {0}.'.format(new_fn))
lyr = ds.GetLayer(0)
if not lyr.TestCapability(ogr.OLCCreateField):
raise RuntimeError('Cannot create fields.')
lyr.CreateField(ogr.FieldDefn('ID', ogr.OFTInteger))
# Now try it with the datasource opened for writing. This is the way the
# book does it, because this is how it should be done.