How to plot vertical lines in plotly offline?

Question

How would one plot a vertical line in plotly offline, using python? I want to add lines at x=20, x=40, and x=60, all in the same plot.

def graph_contracts(self):
    trace1 = go.Scatter(
        x=np.array(range(len(all_prices))),
        y=np.array(all_prices), mode='markers', marker=dict(size=10, color='rgba(152, 0, 0, .8)'))
    data = [trace1]
    layout = go.Layout(title='Market Contracts by Period',
                       xaxis=dict(title='Contract #',
                                  titlefont=dict(family='Courier New, monospace', size=18, color='#7f7f7f')),
                       yaxis=dict(title='Prices ($)',
                                  titlefont=dict(family='Courier New, monospace', size=18, color='#7f7f7f')))
    fig = go.Figure(data=data, layout=layout)
    py.offline.plot(fig)

Answer 1

This is my example. The most important instruction is this.

fig.add_trace(go.Scatter(x=[12, 12], y=[-300,300], mode="lines", name="SIGNAL"))

The most important attribute is MODE='LINES'.

Actually this example is about a segment with x=12

EXAMPLE

    import pandas as pd
    import plotly.graph_objects as go
    import matplotlib.pyplot as plt
    import numpy as np
    import plotly.tools as tls




    df1 = pd.read_csv('./jnjw_f8.csv')



    layout = go.Layout(
    xaxis = go.layout.XAxis(
        tickmode = 'linear',
        tick0 = 1,
        dtick = 3
    ),
    yaxis = go.layout.YAxis(
        tickmode = 'linear',
        tick0 = -100,
        dtick = 3
    ))

    fig = go.Figure(layout = layout)

    fig.add_trace(go.Scatter(x = df1['x'], y = 
    df1['y1'],name='JNJW_sqrt'))
    fig.add_trace(go.Scatter(x=[12, 12], y=[-300,300], 
    mode="lines", name="SIGNAL"))


    fig.show()

Look here too. how to plot a vertical line with plotly