app.py

import altair as alt
import streamlit as st

african_countries = alt.topo_feature(
        "https://raw.githubusercontent.com/deldersveld/topojson/master/continents/africa.json",
        "continent_Africa_subunits",
    )
africa_chart = (
    alt.Chart(african_countries)
    .mark_geoshape(stroke="white", strokeWidth=2)
    .encode(
        color="value:Q",
        tooltip=[
            alt.Tooltip("properties.geounit:O", title="Country name"),
            alt.Tooltip("value:Q", title="Indicator value"),
        ],
    )
    .transform_lookup(
        lookup="properties.geounit",
        from_=alt.LookupData(filtered_data, "Geo Name", ["value"]),
    )
)
st.altair_chart(africa_chart)