def shape_from_pyshp_to_shapely(pyshp_shape, threshold):
"""
convert pyshp object to shapely object
:param pyshp_shape: pyshp (shapefile) object
:return: shapely object if successful, False otherwise
"""
parts_index = pyshp_shape.parts
if len(parts_index) < 2:
# Create a polygon with no holes
record = Polygon(pyshp_shape.points)
else:
# Create a polygon with one or several holes
seperate_parts = []
parts_index.append(len(pyshp_shape.points))
for i in range(0, len(parts_index) - 1):
points = pyshp_shape.points[parts_index[i]:parts_index[i + 1]]
seperate_parts.append(points)
# if list(parts_index)==[0,121,130,135,140]:
# debug = 1
# assuming the first part is exterior
# exterior = seperate_parts[0] # assuming the first part is exterior
# interiors = [seperate_parts[i] for i in range(1,len(seperate_parts))]
# assuming the last part is exterior
# exterior = seperate_parts[len(parts_index)-2]
# interiors = [seperate_parts[i] for i in range(0,len(seperate_parts)-2)]
all_polygons = []
length = len(seperate_parts)
flag = 0
for i in range(length - 1):
if len(seperate_parts[flag]) > len(seperate_parts[i + 1]):
flag = flag
else:
flag = i + 1
threshold = len(seperate_parts[flag]) - 1
while (len(seperate_parts) > 0):
print("the first polygon has %d points" % len(seperate_parts[0]))
#if shapefile.signed_area(seperate_parts[0]) < 0: # the area of ring is clockwise, it's not a hole
#if shapefile.signed_area(seperate_parts[0]) > 0:
if len(seperate_parts[0]) > threshold:
print("the exterior polygon has %d points" %
len(seperate_parts[0]))
exterior = tuple(seperate_parts[0])
seperate_parts.remove(seperate_parts[0])
# find all the holes attach to the first exterior
interiors = []
holes_points = []
for points in seperate_parts:
#if shapefile.signed_area(points) >= 0: # the value >= 0 means the ring is counter-clockwise, then they form a hole
if len(points) < threshold:
interiors.append(tuple(points))
holes_points.append(points)
# remove the parts which are holes
for points in holes_points:
seperate_parts.remove(points)
# else:
# break
if len(interiors) < 1:
interiors = None
else:
interiors = tuple(interiors)
polygon = Polygon(shell=exterior, holes=interiors)
all_polygons.append(polygon)
else:
seperate_parts.remove(seperate_parts[0])
if len(all_polygons) > 1:
record = MultiPolygon(polygons=all_polygons)
else:
record = all_polygons[0]
shapelytogeojson = shapely.geometry.mapping
geoj = shapelytogeojson(record)
# create empty pyshp shape
record = shapefile._Shape()
record.points = geoj["coordinates"][0]
record.shapeType = 5
record.parts = [0]
# # plot shape for checking
# from matplotlib import pyplot as plt
# from descartes import PolygonPatch
# from math import sqrt
# # from shapely.geometry import Polygon, LinearRing
# # from shapely.ops import cascaded_union
# BLUE = '#6699cc'
# GRAY = '#999999'
#
# # plot these two polygons separately
# fig = plt.figure(1, dpi=90) #figsize=SIZE,
# ax = fig.add_subplot(111)
# poly1patch = PolygonPatch(record, fc=BLUE, ec=BLUE, alpha=0.5, zorder=2)
# # poly2patch = PolygonPatch(polygon2, ec=BLUE, alpha=0.5, zorder=2)
# ax.add_patch(poly1patch)
# # ax.add_patch(poly2patch)
# boundary = record.bounds
# xrange = [boundary[0], boundary[2]]
# yrange = [boundary[1], boundary[3]]
# ax.set_xlim(*xrange)
# # ax.set_xticks(range(*xrange) + [xrange[-1]])
# ax.set_ylim(*yrange)
# # ax.set_yticks(range(*yrange) + [yrange[-1]])
# # ax.set_aspect(1)
#
# plt.show()
return record
