GEOSGeom_createLineString_r returned a NULL pointer

[NeighborhoodCoding]

Hi, I'm running your code... but above error comming out...
I just installed geopandas and fiona...

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ValueError Traceback (most recent call last)
in
61 return cascaded_union(triangles), edge_points
62
---> 63 concave_hull, edge_points = alpha_shape(points, alpha=1.87)
64
65 _ = plot_polygon(concave_hull)

in alpha_shape(points, alpha)
57 add_edge(edges, edge_points, coords, ic, ia)
58
---> 59 m = geometry.MultiLineString(edge_points)
60 triangles = list(polygonize(m))
61 return cascaded_union(triangles), edge_points

c:\users\owner\appdata\local\programs\python\python36\lib\site-packages\shapely\geometry\multilinestring.py in init(self, lines)
50 pass
51 else:
---> 52 self._geom, self._ndim = geos_multilinestring_from_py(lines)
53
54 def shape_factory(self, *args):

c:\users\owner\appdata\local\programs\python\python36\lib\site-packages\shapely\geometry\multilinestring.py in geos_multilinestring_from_py(ob)
132 # add to coordinate sequence
133 for l in range(L):
--> 134 geom, ndims = linestring.geos_linestring_from_py(obs[l])
135 subs[l] = cast(geom, c_void_p)
136

c:\users\owner\appdata\local\programs\python\python36\lib\site-packages\shapely\speedups_speedups.pyx in shapely.speedups._speedups.geos_linestring_from_py()

ValueError: GEOSGeom_createLineString_r returned a NULL pointer

do you know why the error appears?

[dwyerk]

Usually this means that the LineString is invalid. You should inspect the value of edge_points to see if it's a reasonable input to MultiLineString.