Create a geopackage file with integer attribute containing NULL values in GeoPandas

Question

I've been asked to produce a geopackage file in a specified format where one attribute is specified to be int64 nullable, and my case includes NULL values. Trying in GeoPandas, my problem is that I don't manage to create a geodataframe with a dtype=int64 containing NULL values.

I've tried adding a list of integer and None values, which becomes floats in the dataframe:

>>> import geopandas as gp
>>> from shapely.geometry import Point
>>> outdf = gp.GeoDataFrame(geometry=[Point(1, 2), Point(2, 1)])
>>> outdf['nulled_int'] = [0, None]
>>> outdf['nulled_int']
0    0.0
1    NaN
Name: nulled_int, dtype: float64

Trying to cast it to integer gives an error:

>>> outdf['nulled_int'] = outdf['nulled_int'].astype(int)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/a002001/develop/lib64/python3.6/site-packages/pandas/core/generic.py", line 5698, in astype
    new_data = self._data.astype(dtype=dtype, copy=copy, errors=errors)
  File "/home/a002001/develop/lib64/python3.6/site-packages/pandas/core/internals/managers.py", line 582, in astype
    return self.apply("astype", dtype=dtype, copy=copy, errors=errors)
  File "/home/a002001/develop/lib64/python3.6/site-packages/pandas/core/internals/managers.py", line 442, in apply
    applied = getattr(b, f)(**kwargs)
  File "/home/a002001/develop/lib64/python3.6/site-packages/pandas/core/internals/blocks.py", line 625, in astype
    values = astype_nansafe(vals1d, dtype, copy=True)
  File "/home/a002001/develop/lib64/python3.6/site-packages/pandas/core/dtypes/cast.py", line 868, in astype_nansafe
    raise ValueError("Cannot convert non-finite values (NA or inf) to integer")
ValueError: Cannot convert non-finite values (NA or inf) to integer

Starting off from a Pandas series of integer type also get casted to float automatically:

>>> import pandas as pd
>>> outdf['nulled_int'] = pd.Series(dtype=int)
>>> outdf['nulled_int']
0   NaN
1   NaN
Name: nulled_int, dtype: float64

The geopackage format seems happy with nullable integer fields, I've made myself a small testfile with two integer attribute fields: nulled_int containing a null value and integers containing only 0 and 1:

$ ogrinfo riket_test.gpkg -al -geom=no -noextent -nomd
    
INFO: Open of `riket_test.gpkg'
      using driver `GPKG' successful.

[...]

nulled_int: Integer64 (0.0)
integers: Integer64 (0.0)
OGRFeature(riket_test):1
  nulled_int (Integer64) = 1
  integers (Integer64) = 1

OGRFeature(riket_test):2
  nulled_int (Integer64) = (null)
  integers (Integer64) = 0

Reading this file into GeoPandas ends up in the same result as in the attempts to create it above: the field containing the NULL value gets casted to float:

>>> df = gp.read_file('riket_test.gpkg')
>>> df['nulled_int']
0    1.0
1    NaN
Name: nulled_int, dtype: float64
>>> df['integers']
0    1
1    0
Name: integers, dtype: int64
>>> 

Answer 1

You could try converting your column to nullable integer data type

outdf['nulled_int'] = outdf['nulled_int'].astype('Int64')

It will get You a bit further:

>> outdf
                  geometry  nulled_int
0  POINT (1.00000 2.00000)           0
1  POINT (2.00000 1.00000)        <NA>