Working with __geo_interface__

Use gpdvega.geojson_feature() to store an object that provides __geo_interface__ support. Module geopandas.GeoDataFrame implements that interface, for list of other supported object see manifest

import altair as alt
import geopandas as gpd
import gpdvega

alt.renderers.enable('notebook') # render for Jupyter Notebook
alt.data_transformers.enable(consolidate_datasets=False) # altair issue #1091

world = gpd.read_file(gpd.datasets.get_path('naturalearth_lowres'))

alt.Chart(
    data = gpdvega.geojson_feature( # converting to GeoJSON object
                world[world.continent=='Africa'],
                "features" # split collection of features into objects
        )
).mark_geoshape(
).project(
).encode(
    fill = alt.Color('id:N',legend=None),
    # data values are stored under nested `properties` object
    tooltip=['properties.name:O'],
).properties(
    width=500,
    height=300
)