"""
Choropleth Map
==============
A choropleth map of unemployment rate per county in the US
"""
# category: maps
import altair as alt
from vega_datasets import data

counties = alt.topo_feature(data.us_10m.url, "counties")
source = data.unemployment()

alt.Chart(counties).mark_geoshape().encode(color="rate:Q").transform_lookup(
    lookup="id", from_=alt.LookupData(source, "id", ["rate"])
).project(type="albersUsa").properties(width=500, height=300)
