This seems inconsistent: ``` In [38]: x = np.array([np.nan, 1, 2, 3]) In [39]: x Out[39]: array([ nan, 1., 2., 3.]) In [40]: x.astype(np.int16) Out[40]: array([0, 1, 2, 3], dtype=int16) In [41]: x.astype(np.int32) Out[41]: array([-2147483648, 1, 2, 3], dtype=int32) In [42]: x.astype(np.int64) Out[42]: array([-9223372036854775808, 1, 2, 3]) ```