Use dataframe index as X axis

Hi, I am trying to use a pandas dataframe as the Chart data in altair, but I need to use the index of the dataframe as the X axis. My dataframe looks like this

with index of type

DatetimeIndex(['2014-04-01 00:00:00', '2014-04-01 00:05:00',
               '2014-04-01 00:10:00', '2014-04-01 00:15:00',
               '2014-04-01 00:20:00', '2014-04-01 00:25:00',
               '2014-04-01 00:30:00', '2014-04-01 00:35:00',
               '2014-04-01 00:40:00', '2014-04-01 00:45:00',
               ...
               '2014-04-14 23:10:00', '2014-04-14 23:15:00',
               '2014-04-14 23:20:00', '2014-04-14 23:25:00',
               '2014-04-14 23:30:00', '2014-04-14 23:35:00',
               '2014-04-14 23:40:00', '2014-04-14 23:45:00',
               '2014-04-14 23:50:00', '2014-04-14 23:55:00'],
              dtype='datetime64[ns]', name='timestamp', length=4032, freq=None)

I tried something like this, but to no use.

from altair import Chart, X, Y
Chart(data1).mark_line().encode(
    X('index'),
    Y('value'),
)

How should I do it? I know that if I convert my index to a column it can do the trick, but is there another way?

[jakevdp]

Altair only recognizes column data; it ignores index values. You can plot the index data by first resetting the index:

Chart(data.reset_index()).mark_line().encode(
    x='index',
    y='value'
)

[nova77]

@afonit Thanks, that works. I apologize for the noob question, but I found it surprisingly difficult to do something as simple, and .reset_index() doesn’t seem very intuitive.