Pandas Cookbook

How to do it...

1. Read in the meetup dataset, convert the join_date column into a Timestamp, place it in the index, and output the first five rows:

>>> meetup = pd.read_csv('data/meetup_groups.csv',                           parse_dates=['join_date'],                           index_col='join_date')>>> meetup.head()

2. Let's get the number of people who joined each group each week:

>>> group_count = meetup.groupby([pd.Grouper(freq='W'), 'group']) \                        .size()>>> group_count.head()join_date   group   
2010-11-07  houstonr     5
2010-11-14  houstonr    11
2010-11-21  houstonr     2
2010-12-05  houstonr     1
2011-01-16  houstonr     2
dtype: int64

3. Unstack the group level so that each meetup group has its own column of data: ...