Re: [Numpy-discussion] Python Magazine

2007-10-07 Thread Alan G Isaac
On Fri, 05 Oct 2007, Christopher Barker apparently wrote:
> There is a new Python Magazine out there: 
> http://www.pythonmagazine.com/ 

Looks useful.
If you think so too, make sure you library subscribes.

Cheers,
Alan Isaac


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[Numpy-discussion] Memory leak in vectorize ?

2007-10-07 Thread Cyrille Rosset
Hello,
the following code seems to create a memory leak in Python.
(around 230 MB).
Any ideas what's wrong ?
I'm using python 2.5 and numpy 1.0.3
---
def toto(x):
 return x**2

tutu=vectorize(toto)

Nbins=1
for i in xrange(1000):
 c=tutu(arange(Nbins))
---

Thanks,
Cyrille.
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[Numpy-discussion] Interested in adding new data type

2007-10-07 Thread Neal Becker
I'm interested in experimenting with adding complex data type.  I
have "Guide to Numpy".  I'm looking at section 15.3. It looks like the
first thing is a PyArray_Desc.  There doesn't seem to be much info on what
needs to go in this.  Does anyone have any examples I could look at?


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Re: [Numpy-discussion] Iterate over all 1-dim views

2007-10-07 Thread Gael Varoquaux
On Sun, Oct 07, 2007 at 06:52:11AM -0400, Neal Becker wrote:
> Suppose I have a function F(), which is defined for 1-dim arguments.  If the
> user passes an n>1 dim array, I want to apply F to each 1-dim view.

> For example, for a 2-d array, apply F to each row and return a 2-d result.

> For a 3-d array, select each 2-d subarray and see above.  Return 3-d result.

> Any suggestions on how to code something like this in numpy?

Code your function so that it works well for 2D arrays (using axis=-1 and
co), then use a decorator on it so that if you pass it an N-d array, it
transforms it in a 2D array, passes it to the decorator, then transforms
the output back to the right shape.

The idea is quite theoretical, and I have never gotten to implement it,
because when I was facing similar problems, it didn't come to my mind,
but I think it can work in a very general way.

Gaƫl
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Re: [Numpy-discussion] Iterate over all 1-dim views

2007-10-07 Thread Pauli Virtanen
Neal Becker <[EMAIL PROTECTED]> kirjoitti: 
> Suppose I have a function F(), which is defined for 1-dim arguments.  If the
> user passes an n>1 dim array, I want to apply F to each 1-dim view.
> 
> For example, for a 2-d array, apply F to each row and return a 2-d result.
> 
> For a 3-d array, select each 2-d subarray and see above.  Return 3-d result.
> 
> Any suggestions on how to code something like this in numpy?

You may be looking for numpy.apply_along_axis:

>>> from numpy import *
>>> x=arange(2*3*4); x.shape=(2,3,4)
>>> x
array([[[ 0,  1,  2,  3],
[ 4,  5,  6,  7],
[ 8,  9, 10, 11]],

   [[12, 13, 14, 15],
[16, 17, 18, 19],
[20, 21, 22, 23]]])
>>> apply_along_axis(cumsum, 0, x)
array([[[ 0,  1,  2,  3],
[ 4,  5,  6,  7],
[ 8,  9, 10, 11]],

   [[12, 14, 16, 18],
[20, 22, 24, 26],
[28, 30, 32, 34]]])
>>> apply_along_axis(cumsum, 1, x)
array([[[ 0,  1,  2,  3],
[ 4,  6,  8, 10],
[12, 15, 18, 21]],

   [[12, 13, 14, 15],
[28, 30, 32, 34],
[48, 51, 54, 57]]])
>>> apply_along_axis(cumsum, 2, x)
array([[[ 0,  1,  3,  6],
[ 4,  9, 15, 22],
[ 8, 17, 27, 38]],

   [[12, 25, 39, 54],
[16, 33, 51, 70],
[20, 41, 63, 86]]])


-- 


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[Numpy-discussion] Iterate over all 1-dim views

2007-10-07 Thread Neal Becker
Suppose I have a function F(), which is defined for 1-dim arguments.  If the
user passes an n>1 dim array, I want to apply F to each 1-dim view.

For example, for a 2-d array, apply F to each row and return a 2-d result.

For a 3-d array, select each 2-d subarray and see above.  Return 3-d result.

Any suggestions on how to code something like this in numpy?

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