Error when changing covering area

[matdeof]

Hello,

I'm using s2 geometry to create a grid over a rectangle. The idea is basically to discretize a given city space, as follows:

Once i have the geometry i'm passing it to the topojson method Topology(dictionary, prequantize=False, topology=True).

The problem is that it only works with some geometries and s2 cells levels, for example when it works for the cell level 13 but it returns an error for cell level 12. I'm running python 3.6.6 and windows 10.

Thanks in advance!

I'm getting this error:

---

TypeError Traceback (most recent call last)
in ()
73 j = j + 1
74
---> 75 tj = topojson.Topology(dictionary)
76 tj.to_json()

c:\users\matheus.ferreira\appdata\local\programs\python\python36\lib\site-packages\topojson\core\topology.py in init(self, data, topology, prequantize, topoquantize, presimplify, toposimplify, simplify_with, simplify_algorithm, winding_order)
94 options = TopoOptions(locals())
95 # execute previous steps
---> 96 super().init(data, options)
97
98 # execute main function of Topology

c:\users\matheus.ferreira\appdata\local\programs\python\python36\lib\site-packages\topojson\core\hashmap.py in init(self, data, options)
20 def init(self, data, options={}):
21 # execute previous step
---> 22 super().init(data, options)
23
24 # initation topology items

c:\users\matheus.ferreira\appdata\local\programs\python\python36\lib\site-packages\topojson\core\dedup.py in init(self, data, options)
26
27 # execute main function of Dedup
---> 28 self.output = self.deduper(self.output)
29
30 def repr(self):

c:\users\matheus.ferreira\appdata\local\programs\python\python36\lib\site-packages\topojson\core\dedup.py in deduper(self, data)
75 # apply linemerge on geoms containing contigious arcs and maintain
76 # bookkeeping
---> 77 self.merge_contigious_arcs(data, sliced_array_bk_ndp)
78
79 # pop the merged contigious arcs and maintain bookkeeping.

c:\users\matheus.ferreira\appdata\local\programs\python\python36\lib\site-packages\topojson\core\dedup.py in merge_contigious_arcs(self, data, sliced_array_bk_ndp)
217
218 # replace linestring of idx_keep with merged linestring
--> 219 data["linestrings"][idx_keep] = ndp_arcs[idx_merg_arc]
220 self.merged_arcs_idx.append(idx_pop)
221

TypeError: list indices must be integers or slices, not NoneType

[mattijn]

Thanks for raising the issue. Could you please provide a small reproducible code snippet of the geometry that gives this error?

[mattijn]

I can reproduce the issue:

import s2sphere as s2
from shapely import geometry
import topojson

region_rect = s2.LatLngRect(
s2.LatLng.from_degrees(-51.264871, -30.241701),
s2.LatLng.from_degrees(-51.04618, -30.000003))
coverer = s2.RegionCoverer()
coverer.min_level=10
coverer.max_level=11
coverer.max_cells=500
covering = coverer.get_covering(region_rect)

geoms = []
for cellid in covering:
    new_cell = s2.Cell(cellid)
    vertices = []
    for i in range(0, 4):
        vertex = new_cell.get_vertex(i)
        latlng = s2.LatLng.from_point(vertex)
        vertices.append((latlng.lat().degrees,latlng.lng().degrees))
    geo = geometry.Polygon(vertices)
    geoms.append(geo)
print("Total Geometries: {}".format(len(geoms)))

geometry.GeometryCollection(geoms)

Total Geometries: 19

topojson.Topology(geoms, prequantize=False, topology=True)

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-2-a207dd4fcbb5> in <module>
----> 1 topojson.Topology(geoms, prequantize=False, topology=True)


~/topojson/topojson/core/topology.py in __init__(self, data, topology, prequantize, topoquantize, presimplify, toposimplify, simplify_with, simplify_algorithm, winding_order)
     94         options = TopoOptions(locals())
     95         # execute previous steps
---> 96         super().__init__(data, options)
     97 
     98         # execute main function of Topology


~/topojson/topojson/core/hashmap.py in __init__(self, data, options)
     20     def __init__(self, data, options={}):
     21         # execute previous step
---> 22         super().__init__(data, options)
     23 
     24         # initation topology items


~/topojson/topojson/core/dedup.py in __init__(self, data, options)
     26 
     27         # execute main function of Dedup
---> 28         self.output = self.deduper(self.output)
     29 
     30     def __repr__(self):


~/topojson/topojson/core/dedup.py in deduper(self, data)
     77             # apply linemerge on geoms containing contigious arcs and maintain
     78             # bookkeeping
---> 79             self.merge_contigious_arcs(data, sliced_array_bk_ndp)
     80 
     81             # pop the merged contigious arcs and maintain bookkeeping.


~/topojson/topojson/core/dedup.py in merge_contigious_arcs(self, data, sliced_array_bk_ndp)
    219 
    220                 # replace linestring of idx_keep with merged linestring
--> 221                 data["linestrings"][idx_keep] = ndp_arcs[idx_merg_arc]
    222                 self.merged_arcs_idx.append(idx_pop)
    223 


TypeError: list indices must be integers or slices, not NoneType

[mattijn]

Previously the Dedup class deduplicate identical arcs and tries to apply a line merge on non-duplicate LineStrings. In this line merging section it assumed that this only could happen on 2 arcs. This assumption proved wrong and is fixed by #51.

[matdeof]

Sorry, the late reply.

Got it, thanks a lot @mattijn !!