Plotly: how to write a text over my Sankey diagram columns?

Question

I've build a Sankey diagram using plotly. I want to name the columns giving each one a column title, like the text in red below:

How can I write these column titles?

Answer 1

It seems like you might actually prefer a parcats diagram instead of a sankey diagram. But if you really want to do this with sankey, a slight modification of Derek O's answer avoids generating the axes you then need to hide. Just use xref="paper" and distribute the x values in the range 0 to 1:

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, A1, B1, ...
      target = [2, 3, 3, 4, 4, 5],
      value = [8, 4, 2, 8, 4, 2]
  ))])

cols = ["column 1","column 2","column 3"]
for x_coordinate, column_name in enumerate(cols):
  fig.add_annotation(
          x=x_coordinate / (len(cols) - 1),
          y=1.05,
          xref="paper",
          yref="paper",
          text=column_name,
          showarrow=False,
          font=dict(
              family="Courier New, monospace",
              size=16,
              color="tomato"
              ),
          align="center",
          )

fig.show()