Write Your Own Geospatial Utilities - Open Source Geospatial Tools: Applications in Earth Observation - page 222

else:
import ogr
import argparse

usage='usage: buffer <infile> <outfile> <distance>'
parser = ArgumentParser()
parser.add_argument("-i","--input", help="Name of input

→

file", dest="inputname", required=True,type="string")
parser.add_argument("-o","--output", help="Name of

→

output file", dest="outputname", required=True,

→ type="string")

parser.add_argument("-d","--distance", help="Buffer

→ distance in map units", dest="distance", required=True,

→ type="string")

args = parser.parse_args()
inputname = args.inputname
outputname = args.outputname
distance = args.distance

if buffer(inputname, outputname, distance):
print 'Buffer succeeded!"
sys.exit(0)

else:
print'Buffer failed!'
sys.exit(1)

We then write a function buffer that accepts the three inputs:

def buffer(infile,outfile,buffdist):
try:

ds_in=ogr.Open( infile )
lyr_in=ds_in.GetLayer( 0 )
drv=ds_in.GetDriver()
if os.path.exists( outfile ):
drv.DeleteDataSource(outfile)
ds_out = drv.CreateDataSource( outfile )

layer = ds_out.CreateLayer(

→

lyr_in.GetLayerDefn().GetName(), \
lyr_in.GetSpatialRef(), ogr.wkbPolygon)
n_fields = lyr_in.GetLayerDefn().GetFieldCount()

for i in xrange ( lyr_in.GetLayerDefn().GetFieldCount()

→

):
field_in = lyr_in.GetLayerDefn().GetFieldDefn( i )
fielddef = ogr.FieldDefn( field_in.GetName(),

→ field_in.GetType() )

layer.CreateField ( fielddef )

featuredefn = layer.GetLayerDefn()

#here we loop through features in the layer
for feat in lyr_in:
geom = feat.GetGeometryRef()
feature = feat.Clone()