1 billion row challenge in a SINGLE EXPRESSION WITH ELIXIR!!

1brc.exs

Mix.install([
  {:explorer, "~> 0.8.0"}
])

# Update to the filepath.
filepath = "./data/weather_stations.csv"

defmodule Challenge do
  import Explorer.Series

  require Explorer.DataFrame, as: DF

  def run(filepath) do
    DF.from_csv!(
        filepath,
        delimiter: ";",
        header: false,
        eol_delimiter: "\n",
        lazy: true,
        dtypes: [column_1: :category, column_2: {:f, 32}]
      )
    |> DF.rename(["station", "measurement"])
    |> DF.group_by("station")
    |> DF.summarise(min: min(measurement), mean: mean(measurement), max: max(measurement))
    |> DF.mutate(min: round(min, 1), mean: round(mean, 1), max: round(max, 1))
    |> DF.sort_by(station)
    |> DF.collect()
    |> DF.to_rows_stream(atom_keys: true)
    |> Stream.map(&("#{&1.station}=#{&1.min}/#{&1.mean}/#{&1.max}"))
    |> Enum.join(", ")
    |> IO.puts()
  end
end


Challenge.run(filepath)

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