Bubble Size Scaling on Charts

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

Section

marker.sizemode controls how marker.size values are interpreted:

• "diameter" (default): size is the diameter in pixels
• "area": size is proportional to area — more perceptually accurate for data comparison

marker.sizeref scales all sizes. Recommended formula: sizeref = 2 * max(size) / max_px^2 where max_px is the desired pixel size of the largest bubble.

alias Plotly.{Figure, Scatter}

sizes = [10, 20, 30, 40, 50]
desired_max_px = 50
sizeref = 2.0 * Enum.max(sizes) / desired_max_px ** 2

Figure.new()
|> Figure.add_trace(
  Scatter.new(
    x: [1, 2, 3, 4, 5],
    y: [1, 2, 3, 4, 5],
    mode: "markers",
    name: "sizemode: area",
    marker: %{
      size: sizes,
      sizemode: "area",
      sizeref: sizeref,
      sizemin: 4
    }
  )
)
|> Figure.update_layout(title: "Bubble Size Scaling (sizemode: area)")
|> Plotly.show()