[Python-Dev] PEP: Adding data-type objects to Python

[Travis Oliphant]

Alexander Belopolsky wrote:
> Travis Oliphant <oliphant.travis <at> ieee.org> writes:
> 
> 
>>>>b = buffer(array('d', [1,2,3]))
> 
> 
> there is not much that I can do with b.  For example, if I want to pass it to
> numpy, I will have to provide the type and shape information myself:
> 
> 
>>>>numpy.ndarray(shape=(3,), dtype=float, buffer=b)
> 
> array([ 1.,  2.,  3.])
> 
> With the extended buffer protocol, I should be able to do
> 
> 
>>>>numpy.array(b)

or just

numpy.array(array.array('d',[1,2,3]))

and leave-out the buffer object all together.


> 
> 
> So let's start by solving this problem and limit it to data that can be found
> in a standard library array.  This way we can postpone the discussion of shapes,
> strides and nested structs.

Don't lump those ideas together.  Shapes and strides are necessary for 
N-dimensional array's (it's essentially what *defines* the N-dimensional 
array).   I really don't want to sacrifice those in the extended buffer 
protocol.  If you want to separate them into different functions then 
that is a possibility.

> 
> If we manage to agree on the standard way to pass primitive type information,
> it will be a big achievement and immediately useful because simple arrays are
> already in the standard library.
> 

We could start there, I suppose.  Especially if it helps us all get on 
the same page.  But, we already see the applications beyond this simple 
case so I would like to have at least an "eye" for the more difficult 
case which we already have a working solution for in the "array interface"

-Travis