numpy-discussion — Discussion list for all users of Numerical Python

Re: [Numpy-discussion] conversion to complex

[Warren F. <fo...@sl...>]

> >>> a=array([1,2,3,4], 'f')
> >>> b=zeros(len(a)/2, 'F')
> >>> b.real=a[0:4:2]
> >>> b.imag=a[1:4:2]
> >>> b
> array([ 1.+2.j,  3.+4.j],'F')

or, if you feel brave

> >>> c=fromstring(a.tostring(), 'F')
> >>> c
> array([ 1.+2.j,  3.+4.j],'F')

wbf

On Tue, 13 Mar 2001, Eric Hagemann wrote:

> I have an array of floats that is an interleaved stream of complex (real/imag) values that I want to promote to complex.  My current method uses the following
> 
> a=array([1,2,3,4])
> 
> b = a[0:4:2] + cmath.sqrt(-1)*a[1:4:2]
> 
> Is there a more elegant way ?  I am hoping to avoid explicit for loops etc
> 

[Numpy-discussion] conversion to complex

[Eric H. <eha...@ho...>]

I have an array of floats that is an interleaved stream of complex =
(real/imag) values that I want to promote to complex.  My current method =
uses the following

a=3Darray([1,2,3,4])

b =3D a[0:4:2] + cmath.sqrt(-1)*a[1:4:2]

Is there a more elegant way ?  I am hoping to avoid explicit for loops =
etc

[Numpy-discussion] Numpy for Windows

[Karl B. <Kar...@um...>]

I am using Numpy and Python 2.1b1 as an internal scripting language for
an NT application. I have the just installed the Numpy 18 Windows
binaries but I believe I need the source, including arrayobject.c and
arrayobject.h. I need them to link them to my application, so I can pass
Numpy Arrays to python. 

I am not having any luck using anonymous CVS to download the current
source. I wonder if the person who just released the windows binary
version could also release the header files and libraries that I need to
link to?


-- 
Cheers,



Karl Bellve

RE: [Numpy-discussion] How to uninstall Numeric-17.3.0.tar.gz

[Paul F. D. <pa...@pf...>]

The "Distutils" used to make the installation does not yet have an
uninstall, but the distutils discussion group has been discussing this
topic. I don't follow the discussion so I can't tell you where they are,
just that I have skipped over a lot of messages on the topic.

Meantime go to your Python root, lib/python20/site-packages, and delete
Numeric.pth, and the directory Numeric. Also directories MA and FFT if you
installed those. Yeah, I know, you didn't want me to tell you that.

-----Original Message-----
From: num...@li...
[mailto:num...@li...]On Behalf Of R. Lahaye
Sent: Tuesday, March 13, 2001 3:36 AM
To: num...@li...
Subject: [Numpy-discussion] How to uninstall Numeric-17.3.0.tar.gz



Hi,

[ I'm not a member of this list, please forward reply also to my personal
email address ]

First of all, I'm not at all familiar with python or numeric python.
I need Numeric for testing a software package on my Linux PC.

I only needed to try the sofware package, so I wanted to temporarily install
Numeric,
How do I do that? I mean, there seems not to be a script for uninstall!?!

The scripts in 17.3.0 only allow me to install. Why is the uninstall
missing?

Or am I overlooking something?

Thanks,
Rob.

PS: don't tell me to go in such and such directory and delete such and such
files.
That would exactly be what scripts are supposed to do.

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[Numpy-discussion] How to uninstall Numeric-17.3.0.tar.gz

[R. L. <la...@po...>]

Hi,

[ I'm not a member of this list, please forward reply also to my personal email address ]

First of all, I'm not at all familiar with python or numeric python.
I need Numeric for testing a software package on my Linux PC.

I only needed to try the sofware package, so I wanted to temporarily install Numeric,
How do I do that? I mean, there seems not to be a script for uninstall!?!

The scripts in 17.3.0 only allow me to install. Why is the uninstall missing?

Or am I overlooking something?

Thanks,
Rob.

PS: don't tell me to go in such and such directory and delete such and such files.
That would exactly be what scripts are supposed to do.

Re: [Numpy-discussion] preventing coercion of matrix

[Warren F. <fo...@sl...>]

That's what the savespace argument to the array constructors is for:

>>> a=Numeric.array(range(4), typecode='f', savespace=1)
>>> a.itemsize()
4
>>> b=a*1.0
>>> b.itemsize()
4

wbf


On Mon, 12 Mar 2001, Mathew Yeates wrote:
> Is there some to prevent the upcast? I realize Python only has double
> datatypes but still .... that shouldnt prevent me from have floats in
> my object.

[Numpy-discussion] preventing coercion of matrix

[Mathew Y. <ma...@fu...>]

Hi-

I'm using Numpy with GL and came across the following problem.

a=ones((2,2),'f')
print a.itemsize()
#result is 4

b=1.0*a
print b.itemsize()
#result is 8

1) I want to pass my array to a GL routine which can only handle floats
also
2) I deal with large data sets and would prefer to keep my array  of type 
float.

Is there some to prevent the upcast? I realize Python only has double datatypes
but still .... that shouldnt prevent me from have floats in my object.

Any help?

Mathew 

[Numpy-discussion] Announcing PyQwt-0.29.x: fast and easy data plotting with Python and NumPy

[Gerard V. <gve...@la...>]

Hi all,

I am announcing PyQwt-0.29.x: fast and easy data plotting with Python and NumPy

see http://gerard.vermeulen.free.fr

This is a set of Python bindings for the Qt-2.x and Qwt-0.3 (Qt Widgets for Technical
Applications) C++ libraries. 

It allows you to create interactively 2D-plots of lists, tuples or NumPy arrays of
Python floats (=C/C++ doubles).


Gerard Vermeulen

[Numpy-discussion] Riccati, Sylvester, Lyapunov matrix equations

[Nils W. <nw...@is...>]

Hi,

I am looking for Python (Numpy, MatPy) routines to solve matrix
equations like Sylvester, Lyapunov and Riccati.

Thanks in advance.

Nils Wagner

[Numpy-discussion] RE: Numpy array matching

[Paul F. D. <pa...@pf...>]

They are being held for an administrative reason, my administrator password
won't work, and I haven't gotten the SourceForge people to fix it yet. I
don't understand the administrative reason since I can't get in to see what
it really is -- something about implicit destination, which is greek to me.
I'm at Spam 9 and can't work on it.

-----Original Message-----
From: Sam Tannous [mailto:sta...@ci...]
Sent: Wednesday, March 07, 2001 11:02 AM
To: Paul F. Dubois
Subject: Numpy array matching


Hi Paul,

My emails to numpy-discussion don't seem to
make it.  Is something wrong at sourceforge?
Is it just me?

Thanks,
Sam
--
Sam Tannous        email: sta...@ci...  )
Software Engineer  phone: 919.392.2541       (
NSITE/SPLoB Tools  pager: 800.365.4578     C[_]

----- Forwarded message from Sam Tannous <sta...@ci...> -----

Date: Wed, 7 Mar 2001 13:51:55 -0500
From: Sam Tannous <sta...@ci...>
Subject: array matching
To: num...@li...

If I have a character array t:

>>> t = array(['abcd','aacd','ddfa','qqcd'])
>>> print t
[[a b c d]
 [a a c d]
 [d d f a]
 [q q c d]]

What's the most efficient way to
create an array that contains the indexes
of the rows that match a particular pattern.

If I want to match a 'c' in the third column,
I'd like the array to look like this:

i = array([0,1,3])

Thanks,
Sam

----- End forwarded message -----

[Numpy-discussion] 18.0 release for Windows

[Paul F. D. <pa...@pf...>]

I made my first attempt at a Windows release,
Numerical-18.0.0-Python2.1.zip. Please note it only works with Python2.1b1.
Comparisons returning array results are now available, thanks to Travis and
his students.

I do not have time to make a source release before Spam 9 so please use CVS
if you need the sources for a Unix build with 2.1b1.

RE: [Numpy-discussion] numpy-17.3.0 build errors

[Paul F. D. <pa...@pf...>]

This issue is fixed in cvs. You can make a directory Numeric in Include and
copy all the .h files down there -- I believe that's the quick fix.
-----Original Message-----
From: num...@li...
[mailto:num...@li...]On Behalf Of
Matthias Klose
Sent: Saturday, March 03, 2001 9:42 AM
To: num...@li...
Subject: [Numpy-discussion] numpy-17.3.0 build errors


On i386-linux I am unable to build on a machine with no previous
version of numpy installed. the arrayobject.h header cannot be found.

Is there a way to actually show the commands use for compiling?

The build procedure then continues to build the other modules and
seems to ignore the return values from the compiler runs.

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[Numpy-discussion] numpy-17.3.0 build errors

[Matthias K. <do...@cs...>]

On i386-linux I am unable to build on a machine with no previous
version of numpy installed. the arrayobject.h header cannot be found.

Is there a way to actually show the commands use for compiling?

The build procedure then continues to build the other modules and
seems to ignore the return values from the compiler runs.

[Numpy-discussion] array_getcharbuf()

[Jack J. <ja...@or...>]

My compiler gives an error on array_getcharbuf() (in arrayobject.c),
and on inspection it looks as though it is right.

Array_getcharbuf() has a char **ptrptr argument, and it passes *ptrptr 
to array_getreadbuf(), which expects a void **. My guess is that it
needs to pass ptrptr, not *ptrptr.

And it definitely needs a cast...

This is all from the repository sources, by the way.
--
Jack Jansen             | ++++ stop the execution of Mumia Abu-Jamal ++++
Jac...@or... | ++++ if you agree copy these lines to your sig ++++
www.oratrix.nl/~jack    | ++++ see http://www.xs4all.nl/~tank/ ++++

Re: [Numpy-discussion] Trouble importing LinearAlgebra

[Robert K. <ke...@it...>]

On Tue, 27 Feb 2001, crag wolfe wrote:

> Well, this a problem that is similar to the one discussed in the "Da
> Blas" thread in September 2000.
> 
> My first command which works fine is "from Numeric import *".  The
> problem is when I "import * from LinearAlgebra" I get "
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
>   File
> "/usr/local/lib/python2.0/site-packages/Numeric/LinearAlgebra.py", line
> 8, in ?
>     import lapack_lite
> ImportError: /usr/lib/liblapack.so.3: undefined symbol: e_wsfe"

Try adding 'g2c' to the list of libraries. You may just end up 
with the same problem as linking with g77, but it's worth a shot.

[snip]

--
Robert Kern
ke...@ca...

"In the fields of hell where the grass grows high
 Are the graves of dreams allowed to die."
  -- Richard Harter

[Numpy-discussion] Proposed agenda for Numeric Bof at Python 9

[Paul B. <Ba...@st...>]

Here is the preliminary agenda for the Enhancing Numeric Python BoF at
Python 9.  We have requested the room for 2 hours (which may not be
enough time to discusss these contentious issues).

Please let me know if you would like a topic added.

 -- Paul



                       Enhancing Numeric Python

                                Agenda


1. Behavior  (~1 hr)

   a. Copy behavior for slice and item syntax

   b. Scalar coercion

   c. Record semantics

   d. Enhanced indexing

2. Implementation  (~1/2 hr)

   a. Type versus class approach

   b. C versus C++

[Numpy-discussion] Trouble importing LinearAlgebra

[crag w. <cr...@ar...>]

Well, this a problem that is similar to the one discussed in the "Da
Blas" thread in September 2000.

My first command which works fine is "from Numeric import *".  The
problem is when I "import * from LinearAlgebra" I get "
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File
"/usr/local/lib/python2.0/site-packages/Numeric/LinearAlgebra.py", line
8, in ?
    import lapack_lite
ImportError: /usr/lib/liblapack.so.3: undefined symbol: e_wsfe"

I'm using Numeric-17.1.2.  I installed the lapack and blas rpms for Red
Hat 6.2, which I'm running.  I edited the setup.py file in the LALITE
directory as indicated.  I run "python setup_all.py install" which seems
to work fine (and I'm clearing out the build directories in between
install attempts).  "gcc -shared
build/temp.linux-i686-2.0/Src/lapack_litemodule.o -lblas -llapack -o
build/lib.linux-i686-2.0/lapack_lite.so" which scrolls by after running
the setup_all.py script, compiles without errors.

After the above failed, I tried manually running g77 in place of gcc (a
hint from the "Da Blas" thread) but then instead of the "undefined
symbol: e_wsfe" error I just get a seg fault.

Any help to get this package installed is much appreciated.
--Crag

Re: [Numpy-discussion] Threading, multi-processors, and Numeric Python

[Joe V. A. <van...@at...>]

OK, I guess I've just discovered the answer to my own question.  [Don't
you just hate that! :-) ]


My C++ extensions that perform the real calculations needed to be
modified to support multiple threads.  By adding the
Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS macros, the Python
interpreter knew it was safe to allow other threads to execute during
computations, just like it allows other threads to execute during I/O.

 To accomodate the Python global thread lock, I needed to change my code
as follows:

my_func()
{

	/* python calls */

        Py_BEGIN_ALLOW_THREADS

        /* computations that don't use python API */


	Py_END_ALLOW_THREADS

	/* python API calls */
}

Now, I can see both processors being used.

-- 
Joe VanAndel  	          
National Center for Atmospheric Research
http://www.atd.ucar.edu/~vanandel/
Internet: van...@uc...

[Numpy-discussion] Threading, multi-processors, and Numeric Python

[Joe V. A. <van...@at...>]

I've written Numeric Python code (with Python 1.5.2) to analyze weather
radar data.  In an attempt to speed up this code, I used threads to
perform some of the computations.  

I'm running on a dual processor Linux machine running 2.4.1 with SMP
enabled.  I'm using Numeric -17.3.0 with Python 1.5.2

When I run the threaded code, and monitor the system with 'top', 1
processor spends much of its time idle, and I rarely see two copies of
my 'compute' thread executing.  Each thread is computing its results
from different arrays.  However, all arrays are referenced from the same
dictionary.

Any ideas on how to get both threads computing at the same time?

Thanks for your help!

-- 
Joe VanAndel  	          
National Center for Atmospheric Research
http://www.atd.ucar.edu/~vanandel/
Internet: van...@uc...

Re: [Numpy-discussion] checking identity of arrays?

[<rl...@st...>]

John J. Lee:

>I must be missing something obvious: how does one check if two variables
>refer to the same array object?

Paul Dubois:

>if a is b:

I thought he was asking something different.  Suppose I do this:

a = zeros(100)
b = a[10:20]

Now b is a view of a's data.  Is there any way to test that
a and b refer to the same data?  (Even if this was not John's
question, I'm curious to know the answer.)

RE: [Numpy-discussion] checking identity of arrays?

[Paul F. D. <pa...@pf...>]

if a is b:
...

-----Original Message-----
From: num...@li...
[mailto:num...@li...]On Behalf Of John
J. Lee
Sent: Friday, February 23, 2001 7:10 AM
To: num...@li...
Subject: [Numpy-discussion] checking identity of arrays?



I must be missing something obvious: how does one check if two variables
refer to the same array object?


John


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Re: [Numpy-discussion] checking identity of arrays?

[Robert K. <ke...@it...>]

On Fri, 23 Feb 2001, John J. Lee wrote:

> I must be missing something obvious: how does one check if two variables
> refer to the same array object?

Python's id() builtin function?

> John

--
Robert Kern
ke...@ca...

"In the fields of hell where the grass grows high
 Are the graves of dreams allowed to die."
  -- Richard Harter

[Numpy-discussion] checking identity of arrays?

[John J. L. <ph...@cs...>]

I must be missing something obvious: how does one check if two variables
refer to the same array object?


John

Re: [Numpy-discussion] Handling underflow

[John J. L. <ph...@cs...>]

On 22 Feb 2001, Victor S. Miller wrote:

> Is there some way of having calculations which cause underflow
> automatically set their result to 0.0?  For example when I take
> exp(a), where a is a floating point array.

Not 'automatically', but:

a = whatever()
choose(greater(a, MAX), (a, MAX))
answer = exp(-a)

any good?  This is with a 1D array -- I haven't used higher dimensions
much.


John

[Numpy-discussion] Handling underflow

[<vi...@id...>]

Is there some way of having calculations which cause underflow
automatically set their result to 0.0?  For example when I take
exp(a), where a is a floating point array.
-- 
Victor S. Miller     | " ... Meanwhile, those of us who can compute can hardly
vi...@id...    | be expected to keep writing papers saying 'I can do the
CCR, Princeton, NJ   | following useless calculation in 2 seconds', and indeed
    08540 USA        | what editor would publish them?"  -- Oliver Atkin