I have a pandas dataframe indexed by DateTime from hour "00:00:00" until hour "23:59:00" (increments by minute, seconds not counted).

```
in: df.index
out: DatetimeIndex(['2018-10-08 00:00:00', '2018-10-08 00:00:00',
           '2018-10-08 00:00:00', '2018-10-08 00:00:00',
           '2018-10-08 00:00:00', '2018-10-08 00:00:00',
           '2018-10-08 00:00:00', '2018-10-08 00:00:00',
           '2018-10-08 00:00:00', '2018-10-08 00:00:00',
           ...
           '2018-10-08 23:59:00', '2018-10-08 23:59:00',
           '2018-10-08 23:59:00', '2018-10-08 23:59:00',
           '2018-10-08 23:59:00', '2018-10-08 23:59:00',
           '2018-10-08 05:16:00', '2018-10-08 07:08:00',
           '2018-10-08 13:58:00', '2018-10-08 09:30:00'],
          dtype='datetime64[ns]', name='DateTime', length=91846, freq=None)

```

Now I want to choose specific intervals, say every 1 minute, or every 1 hour, starting from "00:00:00" and retrieve all the rows that interval apart consecutively.

I can grab entire intervals, say the first hour interval, with 

```
df.between_time("01:00:00","00:00:00")

```

But I want to be able to 

(a) get only all the times that are a specific intervals apart
(b) get all the 1-hour intervals without having to manually ask for them 24 times. How do I increment the DatetimeIndex inside the between\_time command? Is there a better way than that?