Annotations with Log Axes

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

Section

When an axis uses type: "log", annotation coordinates must be specified in log₁₀ space. For a data value v, set the annotation coordinate to :math.log10(v). For example, to annotate the point at y = 1000, set y: :math.log10(1000) which equals 3.0.

alias Plotly.{Figure, Scatter}

Figure.new()
|> Figure.add_trace(
  Scatter.new(
    x: [1, 10, 100, 1_000, 10_000],
    y: [1, 10, 100, 1_000, 10_000],
    mode: "lines+markers"
  )
)
|> Figure.update_layout(
  title: "Annotations on Log Axes",
  xaxis: %{type: "log"},
  yaxis: %{type: "log"},
  annotations: [
    %{
      x: :math.log10(100),
      y: :math.log10(100),
      xref: "x",
      yref: "y",
      text: "y = 100",
      showarrow: true,
      arrowhead: 2,
      ax: 40,
      ay: -40
    },
    %{
      x: :math.log10(10_000),
      y: :math.log10(10_000),
      xref: "x",
      yref: "y",
      text: "y = 10,000",
      showarrow: true,
      arrowhead: 2,
      ax: -60,
      ay: 30
    }
  ]
)
|> Plotly.show()