问TypeError: iter()为Python3返回类型为“Layer”的非迭代器

EN

"The Esri Shapefile or simply a shapefile is a popular geospatial vector
data format for geographic information systems software [1]_."

Parameters
----------
path : file or string
   File, directory, or filename to read.

simplify:  bool
    If ``True``, simplify line geometries to start and end coordinates.
    If ``False``, and line feature geometry has multiple segments, the 
    non-geometric attributes for that feature will be repeated for each 
    edge comprising that feature.

Returns
-------
G : NetworkX graph

Examples
--------
>>> G=nx.read_shp('test.shp') # doctest: +SKIP

References
----------
.. [1] http://en.wikipedia.org/wiki/Shapefile
"""
try:
    from osgeo import ogr
except ImportError:
    raise ImportError("read_shp requires OGR: http://www.gdal.org/")

if not isinstance(path, str):
    return

net = nx.DiGraph()
shp = ogr.Open(path)
for lyr in shp:
    fields = [x.GetName() for x in lyr.schema]
    for f in lyr:
        flddata = [f.GetField(f.GetFieldIndex(x)) for x in fields]
        g = f.geometry()
        attributes = dict(zip(fields, flddata))
        attributes["ShpName"] = lyr.GetName()
        if g.GetGeometryType() == 1:  # point
            net.add_node((g.GetPoint_2D(0)), attributes)
        if g.GetGeometryType() == 2:  # linestring
            last = g.GetPointCount() - 1
            if simplify:
                attributes["Wkb"] = g.ExportToWkb()
                attributes["Wkt"] = g.ExportToWkt()
                attributes["Json"] = g.ExportToJson()
                net.add_edge(g.GetPoint_2D(0), g.GetPoint_2D(last), attributes)
            else:
                # separate out each segment as individual edge
                for i in range(last):
                    pt1 = g.GetPoint_2D(i)
                    pt2 = g.GetPoint_2D(i + 1)
                    segment = ogr.Geometry(ogr.wkbLineString)
                    segment.AddPoint_2D(pt1[0], pt1[1])
                    segment.AddPoint_2D(pt2[0], pt2[1])
                    attributes["Wkb"] = segment.ExportToWkb()
                    attributes["Wkt"] = segment.ExportToWkt()
                    attributes["Json"] = segment.ExportToJson()
                    net.add_edge(pt1, pt2, attributes)

return net