alarms in Altair

gistfile1.txt

import pandas as pd

df = pd.DataFrame([
    ['2018-03-11', '11:03',  86],
    ['2018-03-14', '09:27',  43],
    ['2018-03-14', '12:08',  22],
    ['2018-03-15', '03:13',  140],
    ['2018-03-17', '18:06',  10]],
                    columns=['Date','Time','Duration'])
                    
df['dt'] = pd.to_datetime(df['Date'] +' ' +  df['Time'])
df['ht'] = 1

df['End'] = pd.to_datetime(df['dt']) + pd.to_timedelta(df['Duration'], unit='m')

import altair as alt

chart = alt.Chart(df).mark_bar().encode(
    x=alt.X('dt'),
    y=alt.Y('ht') 
)


rule = alt.Chart(df).mark_rule(color='firebrick').encode(
    alt.X(
        'dt:T',
        timeUnit='yearmonthdate',
        axis=alt.Axis(format='%m/%d', title='Dates of Events')
    ),
    alt.Y(
        'ht',
        scale=alt.Scale(domain=[-10, 10]),
        axis=alt.Axis(title='Event')
    ),
    alt.X2('End')
).properties(
    width=700,
    height=300
)

chart + rule