numpy-discussion

[Numpy-discussion] "Manually" broadcasting arrays in Python

[Robert K. <rob...@gm...>]

Has anyone implemented an easier or more efficient way to broadcast arrays to a 
common shape at the Python level? I was hoping that the broadcast iterator would 
actually provide the broadcasted arrays, but it does not.

I've attached my best pure-Python effort.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

Re: [Numpy-discussion] "Manually" broadcasting arrays in Python

[A. M. A. <per...@gm...>]

On 03/10/06, Robert Kern <rob...@gm...> wrote:
> Has anyone implemented an easier or more efficient way to broadcast arrays to a
> common shape at the Python level? I was hoping that the broadcast iterator would
> actually provide the broadcasted arrays, but it does not.

How about vectorize(lambda *args: args)? Almost works, only it
sometimes segfaults with more than two arguments... but that's clearly
a numpy bug.

A. M. Archibald

Re: [Numpy-discussion] "Manually" broadcasting arrays in Python

[Robert K. <rob...@gm...>]

A. M. Archibald wrote:
> On 03/10/06, Robert Kern <rob...@gm...> wrote:
>> Has anyone implemented an easier or more efficient way to broadcast arrays to a
>> common shape at the Python level? I was hoping that the broadcast iterator would
>> actually provide the broadcasted arrays, but it does not.
> 
> How about vectorize(lambda *args: args)? Almost works, only it
> sometimes segfaults with more than two arguments... but that's clearly
> a numpy bug.

Yeah, a segfault would be problematic. Otherwise, it works and is in fact faster 
than what I wrote.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco

Re: [Numpy-discussion] "Manually" broadcasting arrays in Python

[A. M. A. <per...@gm...>]

On 04/10/06, Robert Kern <rob...@gm...> wrote:

> Yeah, a segfault would be problematic. Otherwise, it works and is in fact faster
> than what I wrote.

It's a bit tricky to trigger but I think it was fixed in 1.0rc1 (in
changeset 3125, in fact:
http://projects.scipy.org/scipy/numpy/changeset/3125 )

Would it be useful for me to contribute the tiny script I wrote to
trigger it as a regression test?

A. M. Archibald

Re: [Numpy-discussion] "Manually" broadcasting arrays in Python

[Stefan v. d. W. <st...@su...>]

On Wed, Oct 04, 2006 at 01:37:55AM -0400, A. M. Archibald wrote:
> Would it be useful for me to contribute the tiny script I wrote to
> trigger it as a regression test?
>=20
> A. M. Archibald
>=20
> from numpy import vectorize, zeros
>=20
> vt =3D vectorize(lambda *args: args)
> # Removing either of the following lines cures the segfault
> vt(zeros((1,2,1)), zeros((2,1,1)), zeros((1,1,2)))
> vt(zeros((1,2,1)), zeros((2,1,1)), zeros((1,1,2)), zeros((2,2)))

I also get a segfault when running this, but the strange thing is that
I can't catch it with valgrind (which also segfaults).

I've filed a ticket at

http://projects.scipy.org/scipy/numpy/ticket/325

Regards
St=E9fan