Color Opacity

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

Section

Setting marker.color to an "rgba(r, g, b, a)" string applies opacity at the colour level — each marker's fill colour has its own alpha. This allows per-point transparency when using a list of colours, and is independent of both trace opacity and marker.opacity.

alias Plotly.{Figure, Scatter}

Figure.new()
|> Figure.add_trace(Scatter.new(
  x: [1, 2, 3, 4, 5],
  y: [3, 5, 2, 6, 4],
  mode: "markers",
  name: "rgba colors",
  marker: %{
    size: 24,
    color: [
      "rgba(255,   0,   0, 1.0)",
      "rgba(255, 128,   0, 0.8)",
      "rgba(  0, 200,   0, 0.6)",
      "rgba(  0,   0, 255, 0.4)",
      "rgba(128,   0, 128, 0.2)"
    ],
    line: %{color: "black", width: 1}
  }
))
|> Figure.update_layout(title: "Color Opacity via rgba() — each marker has its own alpha")
|> Plotly.show()