import plotly.graph_objs as go
from plotly.offline import plot

value = [3,5,2,4,6]
source = [0,0,1,0,3]
target = [1,4,2,3,4]
color = ["blue","yellow","orange","orange","purple"]
label = ["A","B","C1","C2","D"]


data = dict(
    type='sankey',
    arrangement = 'freeform',
    node = dict(
      pad = 15,
      thickness = 20,
      line = dict(
        color = "black",
        width = 0.1
      ),
      groups = [[2,3]],
      label = label,
      color = color,
    ),
    link = dict(
        source = source,
        target = target,
        value = value,
      )
)

layout =  dict(
    title = "Sankey test",
    font = dict(
      size = 10
    )
)
f = go.FigureWidget(data=[data], layout=layout)
plot(f)