In [1]:

import pandas as pd
import numpy as np
import sys

print "\npandas version:",pd.__version__

pandas version: 0.10.0

In [2]:

def gen_l3_mi(nchs,ndets,ntimes):
    "generate a 3-level multi-index dataframe"
    c = ['c'+str(i) for i in range(1,nchs+1)]
    det = ['d'+str(i) for i in range(1,ndets+1)]
    times = ['t'+str(i) for i in range(1,ntimes+1)]
    ind = []
    for ch in c:
        for d in det:
            for t in times:
                ind.append((ch,d,t))
    index = pd.MultiIndex.from_tuples(ind)
    return pd.DataFrame(np.random.randn(nchs*ndets*ntimes,3), 
                      columns=['A','B','C'],index=index)

In [3]:

df = gen_l3_mi(1,2,5)
df

Out[3]:

			A	B	C
c1	d1	t1	-0.268105	1.063887	-1.959510
		t2	-0.887410	0.614846	-0.448357
		t3	0.587298	-0.037883	-0.252485
		t4	-0.415601	1.203818	-0.362764
		t5	-0.596451	-0.179422	-0.256425
	d2	t1	-0.712503	-0.635871	-1.642539
		t2	-1.102127	1.446910	1.628707
		t3	0.700126	-0.211521	0.306729
		t4	0.236699	-1.327817	-0.226565
		t5	-0.644808	-0.262662	0.197099

In [4]:

df['D']=0.0

In [5]:

df.D.ix['c1','d1'].ix['t3':'t5'] = 1
df

Out[5]:

			A	B	C	D
c1	d1	t1	-0.268105	1.063887	-1.959510	0
		t2	-0.887410	0.614846	-0.448357	0
		t3	0.587298	-0.037883	-0.252485	1
		t4	-0.415601	1.203818	-0.362764	1
		t5	-0.596451	-0.179422	-0.256425	1
	d2	t1	-0.712503	-0.635871	-1.642539	0
		t2	-1.102127	1.446910	1.628707	0
		t3	0.700126	-0.211521	0.306729	0
		t4	0.236699	-1.327817	-0.226565	0
		t5	-0.644808	-0.262662	0.197099	0

In [6]:

grouped = df.groupby('D')

In [7]:

for i,j in grouped:
    print 'D:',i
    print 'Actual index[2]:',j.index[0][2]
    print 'First element of levels[2]:',j.index.levels[2][0]

D: 0.0
Actual index[2]: t1
First element of levels[2]: t1
D: 1.0
Actual index[2]: t3
First element of levels[2]: t1

In [7]: