testingtoy.py

import plotly.graph_objects as go

import igraph
from igraph import Graph, EdgeSeq
nr_vertices = 20
v_label = list(map(str, range(nr_vertices)))
G = Graph.Tree(nr_vertices, 3) # 2 stands for children number
lay = G.layout('rt')

position = {k: lay[k] for k in range(nr_vertices)}
Y = [lay[k][1] for k in range(nr_vertices)]
M = max(Y)

es = EdgeSeq(G) # sequence of edges
E = [e.tuple for e in G.es] # list of edges

L = len(position)
Xn = [position[k][0] for k in range(L)]
Yn = [2*M-position[k][1] for k in range(L)]
Xe = []
Ye = []
for edge in E:
    Xe+=[position[edge[0]][0],position[edge[1]][0], None]
    Ye+=[2*M-position[edge[0]][1],2*M-position[edge[1]][1], None]

labels = v_label

fig = go.Figure()
fig.add_trace(go.Scatter(x=Xe,
                   y=Ye,
                   mode='lines',
                   line=dict(color='rgb(210,210,210)', width=1),
                   hoverinfo='none'
                   ))
fig.add_trace(go.Scatter(x=Xn,
                  y=Yn,
                  mode='markers',
                  name='bla',
                  marker=dict(symbol='circle-dot',
                                size=18,
                                color='#6175c1',    #'#DB4551',
                                line=dict(color='rgb(50,50,50)', width=1)
                                ),
                  text=labels,
                  hoverinfo='text',
                  opacity=0.8
                  ))