Labelling Lines with Annotations

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

Section

Instead of a legend, place text annotations at the end of each line using layout.annotations. Set xref: "paper" with x: 1 to anchor to the right edge, and yref: "y" to match the line's y value. Set showarrow: false and use xanchor: "left" to avoid overlapping the line.

alias Plotly.{Figure, Scatter}

years = Enum.to_list(2001..2013)

Figure.new()
|> Figure.add_trace(
  Scatter.new(
    x: years,
    y: [74, 82, 80, 74, 73, 72, 74, 70, 70, 66, 66, 69, 67],
    mode: "lines",
    name: "Rest of world",
    showlegend: false
  )
)
|> Figure.add_trace(
  Scatter.new(
    x: years,
    y: [45, 42, 45, 45, 44, 42, 45, 40, 40, 37, 37, 38, 38],
    mode: "lines",
    name: "China",
    showlegend: false
  )
)
|> Figure.update_layout(
  title: "Labelling Lines with Annotations",
  showlegend: false,
  annotations: [
    %{
      xref: "paper",
      x: 1.0,
      y: 67,
      xanchor: "left",
      yanchor: "middle",
      text: "Rest of world",
      font: %{size: 14},
      showarrow: false
    },
    %{
      xref: "paper",
      x: 1.0,
      y: 38,
      xanchor: "left",
      yanchor: "middle",
      text: "China",
      font: %{size: 14},
      showarrow: false
    }
  ]
)
|> Plotly.show()