split.py 文件源码

def get_convex_hull(shape_name, destination_directory):
    '''
    This method will read all objects from a shape file and create a new one
    with the convex hull of all the geometry points of the first.
    '''
    driver = ogr.GetDriverByName(str('ESRI Shapefile'))
    shape = driver.Open(shape_name, 0)
    layer = shape.GetLayer()
    layer_name = layer.GetName()
    spatial_reference = layer.GetSpatialRef()
    prefix = get_basename(shape_name)
    output_name = create_filename(destination_directory, '%s-hull.shp' % prefix)
    geometries = ogr.Geometry(ogr.wkbGeometryCollection)
    for feature in layer:
        geometries.AddGeometry(feature.GetGeometryRef())
    if os.path.exists(output_name):
        driver.DeleteDataSource(output_name)
    datasource = driver.CreateDataSource(output_name)
    out_layer = datasource.CreateLayer(str('states_convexhull'), spatial_reference, geom_type=ogr.wkbPolygon)
    out_layer.CreateField(ogr.FieldDefn(str('id'), ogr.OFTInteger))
    featureDefn = out_layer.GetLayerDefn()
    feature = ogr.Feature(featureDefn)
    feature.SetGeometry(geometries.ConvexHull())
    feature.SetField(str('id'), 1)
    out_layer.CreateFeature(feature)
    shape.Destroy()
    datasource.Destroy()