in c extension what is easiest way to build a (PyObject) list from an array of doubles?

[Christian Seberino]

In c extension what is easiest way to build a (PyObject) list from an
array of doubles?

I don't think I can do "return Py_BuildValue(. ..) to make a list from
an array can I???

How else can I build and return a list??

Thanks!

Chris+

[Paul Prescod]

Re: in c extension what is easiest way to build a (PyObject) listfrom an array of doubles?

Christian Seberino wrote:
[color=blue]
> In c extension what is easiest way to build a (PyObject) list from an
> array of doubles?[/color]

No. Check out the array module.

Paul Prescod

[seberino@spawar.navy.mil]

Re: in c extension what is easiest way to build a (PyObject) listfrom an array of doubles?

Paul

Thanks. I agree array is great in Python for processing
homogenous lists but what about in **C code** if you must
return a Python list built from a C array?

How do you build a list/tuple/array/ from a C array of numbers?

Chris

On Mon, Feb 02, 2004 at 11:04:13PM -0800, Paul Prescod wrote:[color=blue]
> Christian Seberino wrote:
>[color=green]
> >In c extension what is easiest way to build a (PyObject) list from an
> >array of doubles?[/color]
>
> No. Check out the array module.
>
> Paul Prescod
>
>[/color]

--
_______________ _______________ _________

Christian Seberino, Ph.D.
SPAWAR Systems Center San Diego
Code 2872
49258 Mills Street, Room 158
San Diego, CA 92152-5385
U.S.A.

Phone: (619) 553-9973
Fax : (619) 553-6521
Email: seberino@spawar .navy.mil
_______________ _______________ _________

[Andrew MacIntyre]

Re: in c extension what is easiest way to build a (PyObject) listfrom an array of doubles?

On Tue, 3 Feb 2004 seberino@spawar .navy.mil wrote:
[color=blue]
> How do you build a list/tuple/array/ from a C array of numbers?[/color]

The API docs are what you need to look at.

To create a tuple, call PyTuple_New().

For each element in your C array, build a Python object then use
PyTuple_SetItem () to insert it into the tuple.

--
Andrew I MacIntyre "These thoughts are mine alone..."
E-mail: andymac@bullsey e.apana.org.au (pref) | Snail: PO Box 370
andymac@pcug.or g.au (alt) | Belconnen ACT 2616
Web: http://www.andymac.org/ | Australia

[seberino@spawar.navy.mil]

Re: in c extension what is easiest way to build a (PyObject) listfrom an array of doubles?

Andrew

Thanks. I did it and it looks like it works too.

Chris

On Wed, Feb 04, 2004 at 07:21:15PM +1100, Andrew MacIntyre wrote:[color=blue]
> On Tue, 3 Feb 2004 seberino@spawar .navy.mil wrote:
>[color=green]
> > How do you build a list/tuple/array/ from a C array of numbers?[/color]
>
> The API docs are what you need to look at.
>
> To create a tuple, call PyTuple_New().
>
> For each element in your C array, build a Python object then use
> PyTuple_SetItem () to insert it into the tuple.
>
> --
> Andrew I MacIntyre "These thoughts are mine alone..."
> E-mail: andymac@bullsey e.apana.org.au (pref) | Snail: PO Box 370
> andymac@pcug.or g.au (alt) | Belconnen ACT 2616
> Web: http://www.andymac.org/ | Australia
>[/color]

--
_______________ _______________ _________

Christian Seberino, Ph.D.
SPAWAR Systems Center San Diego
Code 2872
49258 Mills Street, Room 158
San Diego, CA 92152-5385
U.S.A.

Phone: (619) 553-9973
Fax : (619) 553-6521
Email: seberino@spawar .navy.mil
_______________ _______________ _________

[Skip Montanaro]

Re: in c extension what is easiest way to build a (PyObject) listfrom an array of doubles?


Chris> In c extension what is easiest way to build a (PyObject) list
Chris> from an array of doubles?

Chris> I don't think I can do "return Py_BuildValue(. ..) to make a list
Chris> from an array can I???

If the length of the array is known when you write the code I think
something like this will work:

return Py_BuildValue("[dddd]", a[0], a[1], a[2], a[3]);

Chris> How else can I build and return a list??

Something like this (untested, no error checking):

int alen = sizeof(a)/sizeof(a[0]);
PyObject *list_of_floats = PyList_New(alen );
for (i = 0; i < alen; i++) {
PyList_SET_ITEM (list_of_floats , i, PyInt_FromLong( a[i]));
}
return list_of_floats;

Skip