USA Bubble Map

Mix.install([
  {:plotly_ex, "~> 0.3"},
  {:kino, "~> 0.18"}
])

Section

geo.scope: "usa" constrains the map to the contiguous US (plus Alaska and Hawaii). marker.sizemode: "area" ensures bubble area (not diameter) is proportional to the value.

alias Plotly.{Figure, Scattergeo}

cities = ["New York", "Los Angeles", "Chicago", "Houston", "Phoenix",
          "Philadelphia", "San Antonio", "San Diego", "Dallas", "San Jose"]
lat = [40.7128, 34.0522, 41.8781, 29.7604, 33.4484,
       39.9526, 29.4241, 32.7157, 32.7767, 37.3382]
lon = [-74.0060, -118.2437, -87.6298, -95.3698, -112.0740,
       -75.1652, -98.4936, -117.1611, -96.7970, -121.8863]
population = [8_336_817, 3_979_576, 2_693_976, 2_320_268, 1_680_992,
              1_584_064, 1_547_253, 1_423_851, 1_343_573, 1_021_795]

Figure.new()
|> Figure.add_trace(
  Scattergeo.new(
    lat: lat,
    lon: lon,
    mode: "markers",
    text: Enum.map(Enum.zip(cities, population), fn {c, p} ->
      "#{c}<br>Pop: #{p}"
    end),
    hoverinfo: "text",
    marker: %{
      size: Enum.map(population, &(&1 / 50_000)),
      sizemode: "area",
      sizeref: 2,
      color: population,
      colorscale: "Blues",
      showscale: true,
      colorbar: %{title: %{text: "Population"}}
    }
  )
)
|> Figure.update_layout(
  title: "USA Bubble Map — Largest Cities by Population",
  geo: %{
    scope: "usa",
    showland: true,
    landcolor: "#EAEAAE",
    showlakes: true,
    lakecolor: "#BDDDE4"
  }
)
|> Plotly.show()