Extract day and month from a datetime object

Question

I have a column with dates in string format \'2017-01-01\'. Is there a way to extract day and month from it using pandas?

I have converted the column to

Answer 1

Use dt to get the datetime attributes of the column.

In [60]: df = pd.DataFrame({'date': [datetime.datetime(2018,1,1),datetime.datetime(2018,1,2),datetime.datetime(2018,1,3),]})

In [61]: df
Out[61]:
        date
0 2018-01-01
1 2018-01-02
2 2018-01-03

In [63]: df['day'] = df.date.dt.day

In [64]: df['month'] = df.date.dt.month

In [65]: df
Out[65]:
        date  day  month
0 2018-01-01    1      1
1 2018-01-02    2      1
2 2018-01-03    3      1

Timing the methods provided:

Using apply:

In [217]: %timeit(df['date'].apply(lambda d: d.day))
The slowest run took 33.66 times longer than the fastest. This could mean that an intermediate result is being cached.
1000 loops, best of 3: 210 µs per loop

Using dt.date:

In [218]: %timeit(df.date.dt.day)
10000 loops, best of 3: 127 µs per loop

Using dt.strftime:

In [219]: %timeit(df.date.dt.strftime('%d'))
The slowest run took 40.92 times longer than the fastest. This could mean that an intermediate result is being cached.
1000 loops, best of 3: 284 µs per loop

We can see that dt.day is the fastest