strange numpy behaviour

Ian Kelly ian.g.kelly at gmail.com
Wed Oct 8 21:19:32 CEST 2014


On Wed, Oct 8, 2014 at 10:29 AM, George Trojan <george.trojan at noaa.gov> wrote:
> This does not look right:
>
> dilbert at gtrojan> python3.4
> Python 3.4.1 (default, Jul  7 2014, 15:47:25)
> [GCC 4.8.3 20140624 (Red Hat 4.8.3-1)] on linux
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import numpy as np
>>>> a=np.ma.array([0, 1], dtype=np.int8, mask=[1, 0])
>>>> a
> masked_array(data = [-- 1],
>              mask = [ True False],
>        fill_value = 999999)
>
>>>> a.data
> array([0, 1], dtype=int8)
>>>> a.filled()
> array([63,  1], dtype=int8)         <------- Why 63?
>>>>
>
> What do you think?

The datatype is int8, the fill value is the default of 999999, and
999999 & 0xff == 63.



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