pandas - apply datetime functions

Question

I'm going beyond this question to get further information about a datetime dataframe. Working with a DataFrame like this:

User_ID    Datetime
01    2014-01-01 08:00:00
01    2014-02-02 09:00:00
02    2014-01-02 10:00:00
02    2014-01-03 11:00:00
03    2014-01-04 12:00:00
04    2014-01-04 13:00:00
05    2014-01-02 14:00:00
01    2014-04-01 08:00:00
01    2014-03-02 09:00:00
01    2014-05-01 08:00:00
01    2014-06-02 09:00:00
01    2014-07-01 08:00:00
01    2014-08-02 09:00:00
01    2014-09-01 08:00:00
01    2014-10-02 09:00:00
01    2014-11-01 08:00:00
01    2014-12-02 09:00:00

where Users are associated to a particular datetime event. Users can have more occurrences during the year, for instance 12 per month, 100 per day etc, but I would like to filter only the users with AT LEAST one occurrence / every single month of the year. In the above example the User 01.

Primer · Accepted Answer · 2015-04-03 12:55:04Z

2

Here is an alternative way to do it using pandas magic:

df['Datetime'] = pd.to_datetime(df.Datetime)  # You can skip this step if you already have it as Datatime object
df1 = df.groupby(['User_ID', df.Datetime.dt.year]).apply(lambda x: x.Datetime.dt.month.nunique())
ids = df1[df1 >= 12].index.get_level_values('User_ID')
df[df.User_ID.isin(ids)]

Which yields:

    User_ID            Datetime
0         1 2014-01-01 08:00:00
1         1 2014-02-02 09:00:00
7         1 2014-04-01 08:00:00
8         1 2014-03-02 09:00:00
9         1 2014-05-01 08:00:00
10        1 2014-06-02 09:00:00
11        1 2014-07-01 08:00:00
12        1 2014-08-02 09:00:00
13        1 2014-09-01 08:00:00
14        1 2014-10-02 09:00:00
15        1 2014-11-01 08:00:00
16        1 2014-12-02 09:00:00

answered Apr 3, 2015 at 12:55

Primer

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Hamza · Accepted Answer · 2015-04-03 10:07:39Z

1

This is my solution supposing you work on a single year.

df is your DataFrame

for user in df.User_ID.unique():

   months = []

   for d in df.Datetime[df.User_ID == user]:
      months.append(d.month)
   if( len(list(set(months))) == 12):
      print('Im user ' + str(user))

answered Apr 3, 2015 at 10:07

Hamza

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