UnboundLocalError on topojson.topology()

[kbrose]

---------------------------------------------------------------------------
UnboundLocalError                         Traceback (most recent call last)
<ipython-input-15-79e7f2268527> in <module>
----> 1 topojson.topology(zdf.head(2))

~.../lib/python3.6/site-packages/topojson/topology.py in topology(data, snap_vertices, gridsize_to_snap)
     28         data = joiner.main(data, quant_factor=None)
     29     data = cutter.main(data)
---> 30     data = deduper.main(data)
     31     data = hashmapper.main(data)
     32 

~.../lib/python3.6/site-packages/topojson/dedup.py in main(self, data)
    181         del data["bookkeeping_linestrings"]
    182         data["bookkeeping_arcs"] = self.list_from_array(array_bk)
--> 183         data["bookkeeping_shared_arcs"] = array_bk_sarcs.astype(int).tolist()
    184         data["bookkeeping_duplicates"] = self.list_from_array(
    185             data["bookkeeping_duplicates"][dup_pair_list != -99]

UnboundLocalError: local variable 'array_bk_sarcs' referenced before assignment

[mattijn]

Thanks for the first issue on this repo! Glad you give it a try.
Looking to the code you share it seems you do

topojson.topology(zdf.head(2))

Try remove the .head(2), or use zdf.iloc[0:2,:]

[kbrose]

That doesn't change anything. The problem is that the array_bk_sarcs variable is created within an if block only, so if that if condition is not True then you will hit this error.

From within dedup.py:

    def main(self, data):
        # <removed docstring for clarity>

        # deduplicate equal geometries
        # create numpy array from bookkeeping_geoms variable for numerical computation
        array_bk = self.index_array(data["bookkeeping_linestrings"])
        if data["bookkeeping_duplicates"].size != 0:
            array_bk_sarcs, dup_pair_list = self.deduplicate(
                data["bookkeeping_duplicates"], data["linestrings"], array_bk
            )

        # <removed comment block for clarity>

        # prepare to return object
        del data["bookkeeping_linestrings"]
        data["bookkeeping_arcs"] = self.list_from_array(array_bk)
        data["bookkeeping_shared_arcs"] = array_bk_sarcs.astype(int).tolist()
        data["bookkeeping_duplicates"] = self.list_from_array(
            data["bookkeeping_duplicates"][dup_pair_list != -99]
        )

        return data

As you can see, the end of main() expects array_bk_sarcs to ALWAYS exist, but the variable is only created when data["bookkeeping_duplicates"].size != 0.

[mattijn]

Thanks for your clarification. You are right. This happened when trying to compute a topology between geometries without any shared boundaries.

All tests in the phase of deduplication (dedup.py) only included geometries that actually had duplicate boundaries. Solved via c9647cc