altair + japan geojson

test.py

import altair as alt
import pandas as pd
import random
import requests

#geo_json = requests.get('https://github.com/dataofjapan/land/raw/master/japan.topojson').json()
#japan_geo = alt.Data(
#    values=geo_json,
#    format=alt.TopoDataFormat(feature='japan',type='topojson')
#)

geo_json = requests.get('https://github.com/dataofjapan/land/raw/master/japan.geojson').json()
japan_geo = alt.Data(values=geo_json, format=alt.DataFormat(property='features',type='json'))

# idが1～47でそれぞれの県に対応している
source = pd.DataFrame({"id": [i + 1 for i in range(47)], "rate": [ random.uniform(0,5) for _ in range(47)]})

alt.Chart(japan_geo).mark_geoshape(
   stroke='black',
   strokeWidth=1
).encode(
    color='rate:Q'
).transform_lookup(
    lookup='properties.id',
    from_=alt.LookupData(source, 'id', ['rate'])
).project(
    scale=1000,
    center=[139.883565, 36.565725]
).properties(
    width=500,
    height=500
)