[Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread James Turner
The people at STScI put me in touch with Peter Verveer, the author of nd_image. Unfortunately Peter is currently unable to maintain the code (either in numarray or scipy), but he did send me some comments on the problem discussed in this thread. Here's what he said: James. - Hi James, Yes,

[Numpy-discussion] Contiguous flags not quite right yet.

2007-03-22 Thread Charles R Harris
Example. In [18]:a = array([1,2,3]) In [19]:a.flags Out[19]: C_CONTIGUOUS : True F_CONTIGUOUS : True OWNDATA : True WRITEABLE : True ALIGNED : True UPDATEIFCOPY : False In [20]:a.shape = (1,3) In [21]:a.flags Out[21]: C_CONTIGUOUS : True F_CONTIGUOUS : False OWNDATA : True WRITEABLE

Re: [Numpy-discussion] Contiguous flags not quite right yet.

2007-03-22 Thread Travis Oliphant
Charles R Harris wrote: All three shapes are both C_CONTIGUOUS and F_CONTIGUOUS. I think ignoring all 1's in the shape would give the right results for otherwise contiguous arrays because in those positions the index can only take the value 0. I've thought about this before too. But,

Re: [Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread Stefan van der Walt
On Thu, Mar 22, 2007 at 02:41:52PM -0400, Anne Archibald wrote: On 22/03/07, James Turner [EMAIL PROTECTED] wrote: So, its not really a bug, its a undesired feature... It is curable, though painful - you can pad the image out, given an estimate of the size of the window. Yes, this sucks.

Re: [Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread Travis Oliphant
Stefan van der Walt wrote: On Thu, Mar 22, 2007 at 02:41:52PM -0400, Anne Archibald wrote: On 22/03/07, James Turner [EMAIL PROTECTED] wrote: So, its not really a bug, its a undesired feature... It is curable, though painful - you can pad the image out, given an estimate of the

[Numpy-discussion] concatenating 1-D arrays to 2D

2007-03-22 Thread Brian Blais
Hello, I'd like to concatenate a couple of 1D arrays to make it a 2D array, with two columns (one for each of the original 1D arrays). I thought this would work: In [47]:a=arange(0,10,1) In [48]:a Out[48]:array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]) In [49]:b=arange(-10,0,1) In [51]:b

Re: [Numpy-discussion] concatenating 1-D arrays to 2D

2007-03-22 Thread Stefan van der Walt
On Thu, Mar 22, 2007 at 08:13:22PM -0400, Brian Blais wrote: Hello, I'd like to concatenate a couple of 1D arrays to make it a 2D array, with two columns (one for each of the original 1D arrays). I thought this would work: In [47]:a=arange(0,10,1) In [48]:a Out[48]:array([0, 1, 2,

[Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread James Turner
Hi Zachary, OK - I sent Peter the URL for your post... Cheers, James. ___ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion

Re: [Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread Stefan van der Walt
On Thu, Mar 22, 2007 at 04:33:53PM -0700, Travis Oliphant wrote: I would rather opt for changing the spline fitting algorithm than for padding with zeros. From what I understand, the splines used in ndimage have the implicit mirror-symmetric boundary condition which also allows them to

[Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread James Turner
By the way, ringing at sharp edges is an intrinsic feature of higher- order spline interpolation, right? I believe this kind of interpolant is really intended for smooth (band-limited) data. I'm not sure why the pre-filtering makes a difference though; I don't yet understand well enough what the

[Numpy-discussion] numpy types for xml pickling

2007-03-22 Thread Christopher Ball
Hi, Gnosis Utils (http://www.gnosis.cx/download/Gnosis_Utils.More/) contains several modules for XML processing, one of which (xml.pickle) serializes objects to and from XML and has an API compatible with Python's pickle [http://freshmeat.net/projects/gnosisxml/]. The xml.pickle module needs

Re: [Numpy-discussion] concatenating 1-D arrays to 2D

2007-03-22 Thread Sebastian Haase
On 3/22/07, Stefan van der Walt [EMAIL PROTECTED] wrote: On Thu, Mar 22, 2007 at 08:13:22PM -0400, Brian Blais wrote: Hello, I'd like to concatenate a couple of 1D arrays to make it a 2D array, with two columns (one for each of the original 1D arrays). I thought this would work:

Re: [Numpy-discussion] nd_image.affine_transform edge effects

2007-03-22 Thread Zachary Pincus
Hello all, By the way, ringing at sharp edges is an intrinsic feature of higher- order spline interpolation, right? I believe this kind of interpolant is really intended for smooth (band-limited) data. I'm not sure why the pre-filtering makes a difference though; I don't yet understand well

[Numpy-discussion] assignment to array.dtype

2007-03-22 Thread Jan Strube
Hi list, maybe this is a really stupid idea, and I don't want to advertise this, but what actually happens when I reassign the dtype of an object? Does it return the same as array.view? say I have the following code In [64]: b Out[64]: array([[ 0, 1, 2], [ 3, 4, 5], [ 6, 7, 8],

Re: [Numpy-discussion] concatenating 1-D arrays to 2D

2007-03-22 Thread Eric Firing
Sebastian Haase wrote: On 3/22/07, Stefan van der Walt [EMAIL PROTECTED] wrote: On Thu, Mar 22, 2007 at 08:13:22PM -0400, Brian Blais wrote: Hello, I'd like to concatenate a couple of 1D arrays to make it a 2D array, with two columns (one for each of the original 1D arrays). I thought