Marker Opacity

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

Section

marker.opacity makes only the marker symbols transparent — the line connecting them remains fully opaque. This differs from trace opacity, which affects the entire trace uniformly.

alias Plotly.{Figure, Scatter}

xs = Enum.to_list(1..10)

Figure.new()
|> Figure.add_trace(Scatter.new(
  x: xs,
  y: Enum.map(xs, fn x -> :math.sin(x / 2.0) * 3 end),
  mode: "lines+markers",
  name: "marker.opacity: 0.3",
  marker: %{size: 18, color: "steelblue", opacity: 0.3},
  line: %{color: "steelblue", width: 2}
))
|> Figure.add_trace(Scatter.new(
  x: xs,
  y: Enum.map(xs, fn x -> :math.cos(x / 2.0) * 3 end),
  mode: "lines+markers",
  name: "marker.opacity: 1.0",
  marker: %{size: 18, color: "tomato", opacity: 1.0},
  line: %{color: "tomato", width: 2}
))
|> Figure.update_layout(title: "Marker Opacity — line stays fully opaque")
|> Plotly.show()