How to set the color of Sankey diagram lines?

As shown, the line gradients according to the color of the label.


Thank you!

import plotly.graph_objects as go

fig = go.Figure(data=[go.Sankey(
    node = dict(
      pad = 15,
      thickness = 20,
      line = dict(color = "black", width = 0.5),
      label = ["A1", "A2", "B1", "B2", "C1", "C2"],
      color = "blue"
    ),
    link = dict(
      source = [0, 1, 0, 2, 3, 3], # indices correspond to labels, eg A1, A2, A2, B1, ...
      target = [2, 3, 3, 4, 4, 5],
      value = [8, 4, 2, 8, 4, 2]
  ))])

fig.update_layout(title_text="Basic Sankey Diagram", font_size=10)
fig.show()

Hello, Tommy. Are you using Plotly Js or Python code here?
Seems it is not possible get this type of line with gradient color with Python.
Thanks.

Doesnโ€™t do what you want, but we have been using this code to calculate the โ€œmiddle colorโ€ of two nodes:

    # calculate intermediate color from two colors
    def link_color(col1, col2):
        color = np.sqrt((col1**2 + col2**2)/2)
        return "rgba(%d, %d, %d, 0.4)" % tuple(color)