Scatter Plot Matrix (SPLOM) — Styled

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

Section

showupperhalf: false hides the upper triangle, leaving only the lower half and diagonal. diagonal: %{visible: false} removes the histograms on the diagonal. marker.size can be reduced for denser datasets.

This example uses synthetic 3-variable data to demonstrate multi-class colouring.

alias Plotly.{Figure, Splom}

:rand.seed(:exsss, {7, 14, 21})

# 3 clusters of 20 points each, encoded as class 0/1/2
gen_cluster = fn n, cx, cy, cz ->
  for _ <- 1..n do
    x = cx + ((for _ <- 1..12, do: :rand.uniform()) |> Enum.sum() |> Kernel.-(6.0))
    y = cy + ((for _ <- 1..12, do: :rand.uniform()) |> Enum.sum() |> Kernel.-(6.0))
    z = cz + ((for _ <- 1..12, do: :rand.uniform()) |> Enum.sum() |> Kernel.-(6.0))
    {x, y, z}
  end
end

all = gen_cluster.(20, 0, 0, 0) ++ gen_cluster.(20, 5, 3, 2) ++ gen_cluster.(20, -4, 4, -2)
x_vals = Enum.map(all, fn {x, _, _} -> x end)
y_vals = Enum.map(all, fn {_, y, _} -> y end)
z_vals = Enum.map(all, fn {_, _, z} -> z end)
classes = List.duplicate(0, 20) ++ List.duplicate(1, 20) ++ List.duplicate(2, 20)

Figure.new()
|> Figure.add_trace(
  Splom.new(
    dimensions: [
      %{label: "Feature A", values: x_vals},
      %{label: "Feature B", values: y_vals},
      %{label: "Feature C", values: z_vals}
    ],
    marker: %{
      color: classes,
      colorscale: "Portland",
      size: 4,
      showscale: false
    },
    showupperhalf: false,
    diagonal: %{visible: false}
  )
)
|> Figure.update_layout(title: "Styled SPLOM — Lower Half Only")
|> Plotly.show()