>>> a = np.array([24,12,57])
>>> a.dtype
dtype('int32')
>>>
>>> a2 = a.astype(np.float64)
>>> a2.dtype
dtype('float64')
>>> fa = np.array([3.45,12.87,87.88])
>>> fa2 = fa.astype(np.int64)
>>> fa2
array([ 3, 12, 87], dtype=int64)