Splitting pandas dataframe into many chunks

Question

Let\'s say I have a dataframe with the following structure:

    observation
d1  1
d2  1
d3  -1
d4  -1
d5  -1
d6  -1
d7  1
d8  1
d9  1
d10 1
d11 -1
d12 -1
d13         


        

Answer 1

Here's an example using real date.datetime objects as indices.

import pandas as pd
import numpy as np
import datetime
import random

df = pd.DataFrame({'x': np.random.randn(40)}, index = [date.fromordinal(random.randint(start_date, end_date)) for i in range(40)])

def filter_on_datetime(df, year = None, month = None, day = None):
    if all(d is not None for d in {year, month, day}):
        idxs = [idx for idx in df.index if idx.year == year and idx.month == month and idx.day == day]
    elif year is not None and month is not None and day is None:
        idxs = [idx for idx in df.index if idx.year == year and idx.month == month]
    elif year is not None and month is None and day is None:
        idxs = [idx for idx in df.index if idx.year == year]
    elif year is None and month is not None and day is not None:
        idxs = [idx for idx in df.index if idx.month == month and idx.day == day]
    elif year is None and month is None and day is not None:
        idxs = [idx for idx in df.index if idx.day == day]
    elif year is None and month is not None and day is None:
        idxs = [idx for idx in df.index if idx.month == month]
    elif year is not None and month is None and day is not None:
        idxs = [idx for idx in df.index if idx.year == year and idx.day == day] 
    else:
        idxs = df.index
    return df.ix[idxs]

Running this:

>>> print(filter_on_datetime(df = df, year = 2016, month = 2))
                   x
2016-02-01 -0.141557
2016-02-03  0.162429
2016-02-05  0.703794
2016-02-07 -0.184492
2016-02-09 -0.921793
2016-02-12  1.593838
2016-02-17  2.784899
2016-02-19  0.034721
2016-02-26 -0.142299