Exception raised when saving Geopandas DataFrame into a file

Question

I am trying to apply the method to_file of a Geopandas DataFrame.

My DataFrame contains a column Polygon, a column Point, a string and float columns.

Here the output of the describe method:

<class 'geopandas.geodataframe.GeoDataFrame'>
RangeIndex: 1332 entries, 0 to 1331
Data columns (total 7 columns):
ID 1332 non-null object
geometry 1332 non-null object
centroid 1332 non-null object
epsg4326_longitude 1332 non-null float64
epsg4326_latitude 1332 non-null float64
epsg3857_x 1332 non-null float64
epsg3857_y 1332 non-null float64
dtypes: float64(4), object(3)
memory usage: 72.9+ KB

The specific types are:

Polygon: shapely.geometry.polygon.Polygon
Point: shapely.geometry.point.Point
String: str
Floats: numpy.float64

When I try apply the method to_file i have the following exception:

geo_grid_df.to_file(filename='grid_50km.geojson', driver='GeoJSON')
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-78-d1eb792e5885> in <module>()
----> 1 geo_grid_df.to_file(filename='grid_france_50km.geojson', driver='GeoJSON')
C:\ProgramData\Anaconda3\lib\site-packages\geopandas\geodataframe.py in to_file(self, filename, driver, schema, **kwargs)
 411 """
 412 from geopandas.io.file import to_file
--> 413 to_file(self, filename, driver, schema, **kwargs)
 414 
 415 def to_crs(self, crs=None, epsg=None, inplace=False):
C:\ProgramData\Anaconda3\lib\site-packages\geopandas\io\file.py in to_file(df, filename, driver, schema, **kwargs)
 109 with fiona.open(filename, 'w', driver=driver, crs=df.crs,
 110 schema=schema, **kwargs) as colxn:
--> 111 colxn.writerecords(df.iterfeatures())
 112 
 113 
C:\ProgramData\Anaconda3\lib\site-packages\fiona\collection.py in writerecords(self, records)
 333 if self.mode not in ('a', 'w'):
 334 raise IOError("collection not open for writing")
--> 335 self.session.writerecs(records, self)
 336 self._len = self.session.get_length()
 337 self._bounds = self.session.get_extent()
fiona\ogrext.pyx in fiona.ogrext.WritingSession.writerecs()
fiona\ogrext.pyx in fiona.ogrext.OGRFeatureBuilder.build()
ValueError: Invalid field type <class 'shapely.geometry.point.Point'>

Any ideas?

pandas: 0.20.3 | geopandas: 0.4.0 | fiona: 1.7.10

• user2856: I don't think you can store a point object in the properties (attributes) of a polygon feature.
• Oscar Mike: I drooped the column with Points objects (centroid) and I don't have the exception anymore. Then I dropped the column with Polygons objects (geometry) and I still have the exception. Seems like the only field where you are able to put geographical objects is under "geometry". So how can we have both geographical information exported in a single file?
• joris: Even if GeoPandas would support multiple geometry columns, many geospatial file formats (including GeoJSON) don't support storing multiple geometry columns. One option is to convert the points to a column of x and y coordinates, so you can store them as integers.

Answer 1

Seems like a Geopandas DataFrame has only ONE column geometry [check it here]

So dumping a Geo DataFrame with two columns or more columns with geometry objects is not possible.

I was able to dump my GeoJSON without the Points objects column:

geo_grid_df.drop(labels='centroid', axis=1).to_file(filename='grid_50km.geojson', driver='GeoJSON')

And without the polygons in another one, after setting the points as my new geometry reference.

geo_grid_df.drop(labels='geometry', axis=1).set_geometry('centroid', crs={'init': 'epsg:4326'}).to_file(filename='grid_50km_centroids.geojson', driver='GeoJSON')