vl.markGeoshape({tooltip: true, stroke: '#aaa', strokeWidth: '1'})
.data(seattleZipCodes.features)
.title("Median House Price in Seattle by Zip Code (2017)")
.project(vl.projection('identity').reflectY(true))
.transform(
vl.lookup("properties.GEOID10").from(
vl.data(seattleHousePricesByZipCode)
.key("ZipCode").fields("MedianHousePrice", "ZipCode")
)
)
.encode(
vl.color().fieldQ('MedianHousePrice')
.legend({columns: 3, symbolLimit: 50, title: "Median House Price"}),
vl.tooltip([{field: 'ZipCode', title: "Zip Code"}, {field: 'MedianHousePrice', title: "Median House Price"}])
).width(500).height(500).render();