[Neuroimaging] Nibabel API change - always read as float

[Matthew Brett]

On Mon, Jul 6, 2015 at 5:32 PM, Bertrand Thirion
<bertrand.thirion at inria.fr> wrote:
> +1 we (and more importantly, our students)  should rely as much as possible
> on the standard behavior of numpy arrays and make adequate decisions, rather
> than having to figure out the details of the API of neuroimaging libraries.
> So the defaut should be unchanged.

Your reasoning implies the opposite.   Numpy tries very hard not to
return arrays of unknown or unpredictable data types, and that is the
situation we have here.   The returned datatype from a nibabel image
is essentially arbitrary, in that very few sources of nifti files
place any weight on whether there are non-default scalefactors or not.
At the moment, we do, depend on this, silently, and that is extremely
confusing, and quite contrary to the standard numpy way,

Cheers,

Matthew