Annotated Heatmap

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

Section

texttemplate: "%{z}" prints the z value inside each heatmap cell. textfont: %{color: "...", size: N} styles the annotation text. Use a D3 format string to control decimal places: texttemplate: "%{z:.2f}".

alias Plotly.{Figure, Heatmap}

z = [
  [1,  20, 30],
  [20, 1,  60],
  [30, 60, 1 ]
]

Figure.new()
|> Figure.add_trace(
  Heatmap.new(
    z: z,
    x: ["Col A", "Col B", "Col C"],
    y: ["Row 1", "Row 2", "Row 3"],
    texttemplate: "%{z}",
    textfont: %{color: "white", size: 14},
    colorscale: "Blues"
  )
)
|> Figure.update_layout(title: "Annotated Heatmap")
|> Plotly.show()