Zero Line Layer

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

Section

layer: "below traces" on an axis moves the entire axis (grid, zero line) below the trace rendering layer, so bars or filled areas draw on top of the zero line. The default is "above traces".

alias Plotly.{Figure, Bar}

x = ["A", "B", "C", "D"]
y = [-5, 3, -2, 8]

Figure.new()
|> Figure.add_trace(Bar.new(x: x, y: y))
|> Figure.update_layout(
  title: "Zero Line Layer: above traces (default)",
  yaxis: %{
    zeroline: true,
    zerolinecolor: "red",
    zerolinewidth: 3
  }
)
|> Plotly.show()

Figure.new()
|> Figure.add_trace(Bar.new(x: x, y: y))
|> Figure.update_layout(
  title: "Zero Line Layer: below traces",
  yaxis: %{
    zeroline: true,
    zerolinecolor: "red",
    zerolinewidth: 3,
    layer: "below traces"
  }
)
|> Plotly.show()