[Numpy-discussion] Unwanted upcast from uint64 to float64

[Travis Oliphant]

Torgil Svensson wrote:
> I'm using windows datetimes (100nano-seconds since 0001,1,1) as time
> in a numpy array and was hit by this behaviour.
>
>   
>>>> numpy.__version__
>>>>         
> '1.0b4'
>   
>>>> a=numpy.array([632925394330000000L],numpy.uint64)
>>>> t=a[0]
>>>> t
>>>>         
> 632925394330000000L
>   
>>>> type(t)
>>>>         
> <type 'numpy.uint64'>
>   
>>>> t+1
>>>>         
> 6.3292539433e+017
>   
>>>> type(t+1)
>>>>         
> <type 'numpy.float64'>
>   
>>>> t==(t+1)
>>>>         
> True
>
> I was trying to set t larger than any time in an array. Is there any
> reason for the scalar to upcast in this case?
>   
Yes, because you are adding a signed scalar to an unsigned scalar and a 
float64 is the only thing that can handle it (well actually it should be 
the long double scalar but we've made a special case here because long 
doubles are not that common).   Add an unsigned scalar

t+numpy.uint64(1)

to get what you want.

-Travis


> //Torgil
>
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