Country GDP Choropleth Map

Mix.install([
  {:plotly_ex, "~> 0.3"},
  {:kino, "~> 0.18"},
  {:req, "~> 0.5"}
])

Section

World GDP data fetched from Plotly's datasets. colorscale: "Plasma" works well for economic data spanning several orders of magnitude. reversescale: true makes higher values darker.

alias Plotly.{Figure, Choropleth}

url = "https://raw.githubusercontent.com/plotly/datasets/master/2014_world_gdp_with_codes.csv"
body = Req.get!(url).body

[header | rows] = String.split(body, "\n", trim: true)
keys = String.split(header, ",") |> Enum.map(&String.trim/1)

data =
  rows
  |> Enum.map(fn row ->
    values = String.split(row, ",")
    Enum.zip(keys, values) |> Map.new()
  end)
  |> Enum.filter(fn r -> match?({_, _}, Float.parse(r["GDP (BILLIONS)"] || "")) end)

locations = Enum.map(data, & &1["CODE"])
gdp = Enum.map(data, &(elem(Float.parse(&1["GDP (BILLIONS)"]), 0)))
text = Enum.map(data, fn r -> "#{r["COUNTRY"]}: $#{r["GDP (BILLIONS)"]}B" end)

Figure.new()
|> Figure.add_trace(
  Choropleth.new(
    locations: locations,
    z: gdp,
    text: text,
    locationmode: "ISO-3",
    colorscale: "Plasma",
    reversescale: true,
    colorbar: %{title: %{text: "GDP (Billions USD)"}},
    hoverinfo: "text"
  )
)
|> Figure.update_layout(
  title: "World GDP — 2014",
  geo: %{
    showframe: false,
    showcoastlines: false,
    projection: %{type: "natural earth"}
  }
)
|> Plotly.show()