In [7]: import pandas as pd In [8]: import numpy as np In [9]: a = np.zeros(5, dtype=np.float) In [10]: df = pd.DataFrame({"foo": [10, 20, 30, 40, 50]}) In [11]: df.index Out[11]: Int64Index([0, 1, 2, 3, 4], dtype='int64') In [12]: df.index * 3.2 Out[12]: Int64Index([0.0, 3.2, 6.4, 9.6, 12.8], dtype='float64') In [13]: a - df.index * 3.2 --------------------------------------------------------------------------- TypeError Traceback (most recent call last) <ipython-input-13-8a6574b7beca> in <module>() ----> 1 a - df.index * 3.2 TypeError: unsupported operand type(s) for -: 'numpy.ndarray' and 'Int64Index' In [14]: pd.__version__ Out[14]: '0.15.0'