https://medium.com/@mmas/simple-web-analytics-with-python-and-pandas-1e890cbeebe0

get_visits.py

def get_visits(groupby):
    ip_visits = data.groupby(groupby)['ip']
    return pd.DataFrame(
        {'unique_visits': ip_visits.apply(lambda x: len(set(x))),
         'total_visits': ip_visits.apply(len)})

data['date_day'] = data['date'].apply(datetime.date)
visits_by_date = get_visits('date_day')
# Redefine with date index to avoid lack of dates.
visits_by_date = pd.DataFrame(visits_by_date,
                              index=pd.date_range(date_0, date_1)).fillna(0)
# Rest of filtered visits.
visits_by_os = get_visits('os')
visits_by_city = get_visits('city')