dissolve does not accept multiple columns to groupBy

[toihr]

In the GeoPandas implementation you can dissolve by multiple columns (by grouping by multiple columns) i.e.

blotch_gpd.dissolve(["obsid","tile_id"])

when this is done in dask_geopandas i obtain the following error:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[37], line 7
      5 result3 = dgp.from_dask_dataframe(blotch_dd,geometry=result2.compute())
      6 result3 = result3.set_crs("EPSG:27700")
----> 7 result4 = result3.dissolve(["obsid","tile_id"])

File ~/.miniforge3/envs/planetary/lib/python3.9/site-packages/dask_geopandas/expr.py:733, in GeoDataFrame.dissolve(self, by, aggfunc, split_out, **kwargs)
    731     data_agg = aggfunc
    732 else:
--> 733     data_agg = {col: aggfunc for col in self.columns.drop(drop)}
    734 data_agg[self.geometry.name] = merge_geometries
    735 # dask 2022.8.1 added shuffle keyword, enabled by default if split_out > 1
    736 # starting with dask 2022.9.1, but geopandas doesn't yet work with shuffle
    737 # https://github.com/geopandas/dask-geopandas/pull/229

File ~/.miniforge3/envs/planetary/lib/python3.9/site-packages/pandas/core/indexes/base.py:7066, in Index.drop(self, labels, errors)
   7063     arr_dtype = "object" if self.dtype == "object" else None
   7064     labels = com.index_labels_to_array(labels, dtype=arr_dtype)
-> 7066 indexer = self.get_indexer_for(labels)
   7067 mask = indexer == -1
   7068 if mask.any():

File ~/.miniforge3/envs/planetary/lib/python3.9/site-packages/pandas/core/indexes/base.py:6182, in Index.get_indexer_for(self, target)
   6164 """
...
File index.pyx:351, in pandas._libs.index.IndexEngine.get_indexer()

File pandas/_libs/hashtable_class_helper.pxi:7132, in pandas._libs.hashtable.PyObjectHashTable.lookup()

TypeError: unhashable type: 'list'