for i in range(100,3000):
  if df.iloc[i]['BoolCol']== True:
     print i,df.iloc[i]['BoolCol']

df = pd.DataFrame({'BoolCol': [True, False, False, True, True]},
    index=[10,20,30,40,50])
In [53]: df
Out[53]: 
  BoolCol
10  True
20  False
30  False
40  True
50  True
[5 rows x 1 columns]
In [54]: df.index[df['BoolCol']].tolist()
Out[54]: [10, 40, 50]

In [56]: idx = df.index[df['BoolCol']]
In [57]: idx
Out[57]: Int64Index([10, 40, 50], dtype='int64')

In [58]: df.loc[idx]
Out[58]: 
  BoolCol
10  True
40  True
50  True

[3 rows x 1 columns]

In [55]: df.loc[df['BoolCol']]
Out[55]: 
  BoolCol
10  True
40  True
50  True

[3 rows x 1 columns]

In [110]: np.flatnonzero(df['BoolCol'])
Out[112]: array([0, 3, 4])

In [113]: df.iloc[np.flatnonzero(df['BoolCol'])]
Out[113]: 
  BoolCol
10  True
40  True
50  True
python pandas