Different implementations follow different conventions as to which
is which.
thank you for the replies ..the reason why i asked was that the most
significant eigenvectors ( sorted according to eigenvalues) are later
used in calculations and then the results obtained differ in java and
Your matrix is almost singular, is badly conditionned,
Mathew, can you explain that..i didn't quite get it..
dn
The condition number is the ratio between the biggest eigenvalue and the
lowest one. In your case, it is 10E-16, so the precision of the double
numbers. That means that some
The vectors that you used to build your covariance matrix all lay in or close
to
a 3-dimensional subspace of the 4-dimensional space in which they were
represented. So one of the eigenvalues of the covariance matrix is 0, or close
to it; the matrix is singular. Condition is the ratio of the
On Tue, Feb 19, 2008 at 05:36:52PM -0700, Charles R Harris wrote:
On Feb 19, 2008 2:20 PM, Stefan van der Walt [EMAIL PROTECTED] wrote:
On Tue, Feb 19, 2008 at 01:50:04PM -0700, Charles R Harris wrote:
And here I thought you were going to fix that. Deleting the
blahs isn't a
On Feb 20, 2008 1:00 AM, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
Different implementations follow different conventions as to which
is which.
thank you for the replies ..the reason why i asked was that the most
significant eigenvectors ( sorted according to eigenvalues) are later
used
I've been browsing the numpy source. I'm wondering about mixed-mode
arithmetic on arrays. I believe the way numpy handles this is that it
never does mixed arithmetic, but instead converts arrays to a common type.
Arguably, that might be efficient for a mix of say, double and float.
Maybe not.
How are you using the values? How significant are the differences?
i am using these eigenvectors to do PCA on a set of images(of faces).I
sort the eigenvectors in descending order of their eigenvalues and
this is multiplied with the (orig data of some images viz a matrix)to
obtain a
You should have such differences, that's strange. Are you sure you're using
the correct eigenvectors ?
Matthieu
2008/2/20, [EMAIL PROTECTED] [EMAIL PROTECTED]:
How are you using the values? How significant are the differences?
i am using these eigenvectors to do PCA on a set of
Hi,
I would also like to know what Java package you're using. I find Weka PCA
differs from Matlab (whereas previous experiments with Scipy PCA didn't show
significant differences from Matlab), but I'm still looking into the cause.
Thanks, and greetings,
Javier Torres
-Original
On Wed, Feb 20, 2008 at 1:22 AM, Nils Wagner
[EMAIL PROTECTED] wrote:
On Tue, 19 Feb 2008 17:10:10 -0600
Sameer DCosta [EMAIL PROTECTED] wrote:
Hi,
I'm getting a segfault when using python objects with
record arrays.
The code (below) basically assigns a single datetime
object
Is there a way to rename record array fields without making a copy of
the whole record array?
Thanks in advance for your replies.
Sameer
___
Numpy-discussion mailing list
Numpy-discussion@scipy.org
We recently deprecated matplotlib.mlab.hist, and I am now hitting a
bug in numpy's historgram, which appears to be caused by the use of
any that does not exist in the namespace. Small patch attached.
The example below exposes the bug:
Python 2.4.2 (#1, Feb 23 2006, 12:48:31)
Type copyright,
On Wed, Feb 20, 2008 at 3:10 PM, Sameer DCosta [EMAIL PROTECTED] wrote:
Is there a way to rename record array fields without making a copy of
the whole record array?
Make a new dtype object with the new names. Use the .view() method on
arrays to get a view of the array with the new dtype.
In
On Wed, Feb 20, 2008 at 3:49 PM, John Hunter [EMAIL PROTECTED] wrote:
We recently deprecated matplotlib.mlab.hist, and I am now hitting a
bug in numpy's historgram, which appears to be caused by the use of
any that does not exist in the namespace. Small patch attached.
Fixed in SVN. Thank
On Wed, 20 Feb 2008, John Hunter apparently wrote:
File
/home/titan/johnh/dev/lib/python2.4/site-packages/numpy/lib/function_base.py,
line 155, in histogram
if(any(bins[1:]-bins[:-1] 0)):
NameError: global name 'any' is not defined
``any`` was introduced in Python 2.5, so you
Hi Sameer
On Wed, Feb 20, 2008 at 03:10:16PM -0600, Sameer DCosta wrote:
Is there a way to rename record array fields without making a copy of
the whole record array?
Thanks in advance for your replies.
Simply view the array as a new dtype:
In [2]: x
Out[2]:
array([(1, 2), (3, 4)],
Hi everybody,
In writing some generic code, I've encountered situations where it would
reduce code complexity to allow NumPy scalars to be indexed in the
same number of limited ways, that 0-d arrays support.
For example, 0-d arrays can be indexed with
* Boolean masks
* Ellipses
A Thursday 21 February 2008, Travis E. Oliphant escrigué:
Hi everybody,
In writing some generic code, I've encountered situations where it
would reduce code complexity to allow NumPy scalars to be indexed
in the same number of limited ways, that 0-d arrays support.
For example, 0-d arrays
On 21.02.2008, at 08:41, Francesc Altet wrote:
Well, it seems like a non-intrusive modification, but I like the
scalars
to remain un-indexable, mainly because it would be useful to raise an
error when you are trying to index them. In fact, I thought that when
you want a kind of scalar but
Travis E. Oliphant wrote:
Hi everybody,
In writing some generic code, I've encountered situations where it would
reduce code complexity to allow NumPy scalars to be indexed in the
same number of limited ways, that 0-d arrays support.
For example, 0-d arrays can be indexed with
*
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