Has anyone got any advice about array creation. I've been using numpy
for a long time and have just noticed something unexpected about array
concatenation.
It seems that using numpy.array([a,b,c]) is around 20 times slower
than creating an empty array and adding the individual elements.
Other
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David Goldsmith skrev:
Interesting comment: it made me run down the fftpack tutorial
http://docs.scipy.org/scipy/docs/scipy-docs/tutorial/fftpack.rst/
josef has alluded to in the past to see if the suggested pointer
could point
It looks like np.savetxt is pretty flexible, accepting fmt, and delimiter
args. But to format into a string, we have array_repr and array_str, which
are not flexible.
Of course, one can use np.savetxt with python stringio, but that's more
work. Would be nice if np.savetxt could just return a
On Thu, Jul 15, 2010 at 5:54 AM, John Porter jpor...@cambridgesys.com wrote:
Has anyone got any advice about array creation. I've been using numpy
for a long time and have just noticed something unexpected about array
concatenation.
It seems that using numpy.array([a,b,c]) is around 20 times
I am seeing a problem on Solaris since I upgraded to svn HEAD.
np.isinf does not handle np.inf. See ipython session below. I am not
seeing this problem w/ HEAD on an ubuntu linux box I tested on
In [1]: import numpy as np
In [2]: np.__version__
Out[2]: '2.0.0.dev8480'
In [3]: x = np.inf
You're right - I screwed up the timing for the one that works...
It does seem to be faster.
I've always just built arrays using nx.array([]) in the past though
and was surprised
that it performs so badly.
On Thu, Jul 15, 2010 at 2:41 PM, Skipper Seabold jsseab...@gmail.com wrote:
On Thu, Jul
Le jeudi 15 juillet 2010 à 16:05 +0100, John Porter a écrit :
You're right - I screwed up the timing for the one that works...
It does seem to be faster.
I've always just built arrays using nx.array([]) in the past though
and was surprised that it performs so badly.
Can anyone provide an
On Thu, Jul 15, 2010 at 11:05 AM, John Porter jpor...@cambridgesys.com wrote:
You're right - I screwed up the timing for the one that works...
It does seem to be faster.
I've always just built arrays using nx.array([]) in the past though
and was surprised
that it performs so badly.
On
ok - except that vstack doesn't seem to work for 2d arrays (without a
reshape) which is what I'm actually after.
The difference between the numpy.concatenate version and numpy.array is fairly
impressive though, I get a factor of 50x. It would be nice to know why.
On Thu, Jul 15, 2010 at 4:15
On Thu, Jul 15, 2010 at 12:23 PM, John Porter jpor...@cambridgesys.com wrote:
ok - except that vstack doesn't seem to work for 2d arrays (without a
reshape) which is what I'm actually after.
Ah, then you might want hstack. There is also a column_stack and
row_stack if you need to go that
Hello,
I have a list of 4x4 transformation matrices, that I want to dot with
another list of the same size (elementwise).
Making a for loop that calculates the dot product of each is extremely slow,
I thought that maybe it's due to the fact that I have thousands of matrices
and it's a python for
On Thu, Jul 15, 2010 at 3:20 AM, Martin Raspaud martin.rasp...@smhi.sewrote:
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David Goldsmith skrev:
Interesting comment: it made me run down the fftpack tutorial
http://docs.scipy.org/scipy/docs/scipy-docs/tutorial/fftpack.rst/
Could you place all Rot's into the same array and all the Trans's into the
same array? If you have the first index of each array refer to which array
it is numpy.dot should work fine, since numpy.dot just does the dot product
over the second to last and last indexes.
On Thu, Jul 15, 2010 at 9:38 AM, Emmanuel Bengio beng...@gmail.com wrote:
Hello,
I have a list of 4x4 transformation matrices, that I want to dot with
another list of the same size (elementwise).
Making a for loop that calculates the dot product of each is extremely slow,
I thought that
On Thu, Jul 15, 2010 at 9:45 AM, Keith Goodman kwgood...@gmail.com wrote:
On Thu, Jul 15, 2010 at 9:38 AM, Emmanuel Bengio beng...@gmail.com wrote:
Hello,
I have a list of 4x4 transformation matrices, that I want to dot with
another list of the same size (elementwise).
Making a for loop
On Thu, Jul 15, 2010 at 10:38 AM, Emmanuel Bengio beng...@gmail.com wrote:
Hello,
I have a list of 4x4 transformation matrices, that I want to dot with
another list of the same size (elementwise).
Making a for loop that calculates the dot product of each is extremely
slow,
I thought that
Hello, all.
Is there a technical reason that 'meshgrid' and 'mgrid' produce results
which differ from each other by a transpose? For example,
In [1]: X,Y = meshgrid(array([0,1,2,3]), array([0,1,2,3,4,5]))
In [2]: X
Out[2]:
array([[0, 1, 2, 3],
[0, 1, 2, 3],
[0, 1, 2, 3],
On 07/15/2010 04:54 AM, John Hunter wrote:
I am seeing a problem on Solaris since I upgraded to svn HEAD.
np.isinf does not handle np.inf. See ipython session below. I am not
seeing this problem w/ HEAD on an ubuntu linux box I tested on
In [1]: import numpy as np
In [2]: np.__version__
I get about 60% of the original execution times for about any size of stack.
On 15 July 2010 14:09, Charles R Harris charlesr.har...@gmail.com wrote:
On Thu, Jul 15, 2010 at 12:00 PM, Emmanuel Bengio beng...@gmail.comwrote:
Ok I get it. Thanks!
Numpy syntax that works for me:
On Thu, Jul 15, 2010 at 12:38 PM, Sturla Molden stu...@molden.no wrote:
Sorry for the previous mispost.
This thread remids me of something I've though about for a while: Would
NumPy benefit from an np.ndarraylist subclass of np.ndarray, that has an
O(1) amortized append like Python lists?
On 2010-07-15, at 12:38 PM, Emmanuel Bengio beng...@gmail.com wrote:
Hello,
I have a list of 4x4 transformation matrices, that I want to dot with
another list of the same size (elementwise).
Making a for loop that calculates the dot product of each is extremely slow,
I thought that maybe
Thu, 15 Jul 2010 09:54:12 -0500, John Hunter wrote:
[clip]
In [4]: np.isinf(x)
Warning: invalid value encountered in isinf Out[4]: True
As far as I know, isinf has always created NaNs -- since 2006 it has been
defined on unsupported platforms as
(!isnan((x)) isnan((x)-(x)))
I'll
On 07/15/2010 11:45 AM, Pauli Virtanen wrote:
Thu, 15 Jul 2010 09:54:12 -0500, John Hunter wrote:
[clip]
In [4]: np.isinf(x)
Warning: invalid value encountered in isinf Out[4]: True
As far as I know, isinf has always created NaNs -- since 2006 it has been
defined on unsupported platforms as
On 2010-07-15, at 4:31 PM, David Warde-Farley wrote:
If you need/want more speed than the solution Chuck proposed, you should
check out Cython and Tokyo. Cython lets you write loops that execute at C
speed, whereas Tokyo provides a Cython level wrapper for BLAS (no need to go
through
On Thu, Jul 15, 2010 at 4:28 PM, David Warde-Farley d...@cs.toronto.eduwrote:
On 2010-07-15, at 4:31 PM, David Warde-Farley wrote:
If you need/want more speed than the solution Chuck proposed, you should
check out Cython and Tokyo. Cython lets you write loops that execute at C
speed,
(CCing NumPy-discussion where this really belongs)
On 2010-07-08, at 1:34 PM, cfra...@uci.edu wrote:
Need Complex numbers in the saved file.
Ack, this has come up several times according to list archives and no one's
been able to provide a real answer.
It seems that there is nearly no
On Thu, Jul 15, 2010 at 6:14 PM, Eric Firing efir...@hawaii.edu wrote:
Is it certain that the Solaris compiler lacks isinf? Is it possible
that it has it, but it is not being detected?
Just to clarify, I'm not using the sun compiler, but gcc-3.4.3 on solaris x86
On Thu, Jul 15, 2010 at 7:11 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:14 PM, Eric Firing efir...@hawaii.edu wrote:
Is it certain that the Solaris compiler lacks isinf? Is it possible
that it has it, but it is not being detected?
Just to clarify, I'm not using the
On Thu, Jul 15, 2010 at 6:11 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:14 PM, Eric Firing efir...@hawaii.edu wrote:
Is it certain that the Solaris compiler lacks isinf? Is it possible
that it has it, but it is not being detected?
Just to clarify, I'm not using the
On Thu, Jul 15, 2010 at 7:27 PM, Charles R Harris
charlesr.har...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:11 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:14 PM, Eric Firing efir...@hawaii.edu wrote:
Is it certain that the Solaris compiler lacks isinf? Is it
On Thu, Jul 15, 2010 at 6:42 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 7:27 PM, Charles R Harris
charlesr.har...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:11 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:14 PM, Eric Firing
On Thu, Jul 15, 2010 at 6:55 PM, Charles R Harris charlesr.har...@gmail.com
wrote:
On Thu, Jul 15, 2010 at 6:42 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 7:27 PM, Charles R Harris
charlesr.har...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:11 PM, John Hunter
On Thu, Jul 15, 2010 at 7:09 PM, Charles R Harris charlesr.har...@gmail.com
wrote:
On Thu, Jul 15, 2010 at 6:55 PM, Charles R Harris
charlesr.har...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:42 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 7:27 PM, Charles R Harris
On Thu, Jul 15, 2010 at 6:42 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 7:27 PM, Charles R Harris
charlesr.har...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:11 PM, John Hunter jdh2...@gmail.com wrote:
On Thu, Jul 15, 2010 at 6:14 PM, Eric Firing
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