
In [14]: g = df.unstack('extra')

In [15]: g
Out[15]: 
                            A                   B          
extra                       0         1         0         1
time                                                       
2001-01-01 00:00:00 -1.049613 -0.626010 -0.847744  0.332070
2001-01-01 01:00:00  0.603061 -1.187563  0.945593  0.601507
2001-01-01 02:00:00 -0.374303 -0.026649 -0.622334  1.183866
2001-01-01 03:00:00  0.582750 -1.520763 -0.580339 -0.844924
2001-01-01 04:00:00 -1.203298  1.107855  0.478186  1.179953
2001-01-01 05:00:00  0.362057  1.769170 -2.114747  0.652288

In [16]: g.resample('6H',how='sum')
Out[16]: 
                   A                   B         
extra              0         1         0        1
time                                             
2001-01-01 -1.079346 -0.483959 -2.741385  3.10476

