Mailman 3 February 2010 - NumPy-Discussion

It's be nice if rint
by Neal Becker Feb. 13, 2010

Feb. 13, 2010

It's be nice if rint could directly return a dtype of my choice (an int- type, such as np.int32).

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A few notes...
by Alcides Viamontes Esquivel Feb. 13, 2010

Feb. 13, 2010

Hello everybody. I has been working with Numpy, I have enjoyed it a lot. Such a great idea to let you do things in Python while the real number-crunching code runs in C. I had to figure out how to do a few things with indexing and would like to share it, you might check it at http://www.scribd.com/full/26811489?access_key=key-2m6kuskw266wnjdsuioe If anyone is interested in the original sources, please contact me directly at a( d o t )viamontes( d o t )esquivel( a t )g m a i l( d o t )c o m Regards!

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Re ading scientific notation using D instead of E
by Robert C. Feb. 12, 2010

Feb. 12, 2010

I am trying to read a large amount of data that is output in scientific notation using D instead of E. After searching around I found a thread that implied numpy already has the capability to do this: http://stackoverflow.com/questions/1959210/python-scientific-notation-using… http://stackoverflow.com/questions/1959210/python-scientific-notation-using… However, this does not work for me. I get: >>> numpy.float('1.23D+04') Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: invalid literal for float(): 1.23D+04 Was this capability lost in more recent versions of numpy? I would rather not have to do a search and replace every time I read in data. Thanks. -- View this message in context: http://old.nabble.com/Reading-scientific-notation-using-D-instead-of-E-tp27… Sent from the Numpy-discussion mailing list archive at Nabble.com.

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Removing datetime support for 1.4.x series ?
by David Cournapeau Feb. 12, 2010

Feb. 12, 2010

Hi, This is a follow-up of the discussion about ABI-breakage in Numpy 1.4.0. To sum it up, it is caused by the new datetime support, and it seems difficult to fix without removing datetime support altogether for the 1.4.x series. Both Chuck and myself are in favor of removing the datetime altogether for 1.4.x as a solution. At least in my case, it is mostly justified by the report from David Huard that the current datetime support is still a bit too experimental to be useful for people who rely on binaries. Are there any objections ? I know in particular Travis was against it when it was suggested, but it was not known at that time that the datetime support would break the ABI (I would have been more strongly against it if I knew at that time). The alternative is to just signal a breakage of the ABI in NumPy 1.4.1. I would like to solve this issue ASAP, as it is quite a burden for people who rely on binaries (changing the ABI would at least generate a useful message instead of weird failures / crashes). cheers, David

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Fwd: [atlas-devel] ATLAS support letters
by Matthew Brett Feb. 12, 2010

Feb. 12, 2010

Hi, I don't know if y'all are subscribed to the ATLAS mailing list, but, it would be good if we could find a way of supporting Clint as strongly as we can. Best, Matthew ---------- Forwarded message ---------- From: Clint Whaley <whaley(a)cs.utsa.edu> Date: Fri, Feb 12, 2010 at 9:15 AM Subject: [atlas-devel] ATLAS support letters To: math-atlas-devel(a)lists.sourceforge.net Guys, I go up for tenure this year. The tenure committee has asked me to get letters of support from ATLAS users so that they can assess the service impact of my support of ATLAS (I *tell* them it is widely used, but can I show it other than downloads?). The letter would discuss a little of what you do, and how you use ATLAS, and the importance of having ATLAS in furthering your project goals. So, if you are part of an organization/business/open source project/research project that uses ATLAS, please contact me if you or a colleague is willing to help with such a letter. If you know someone at such a place that uses ATLAS, forward this on. I will be contacting some groups that I know use ATLAS, but I don't know about the majority of people/groups who do, and I often don't have records and so forget even the ones I knew used it . . . With Goto taking a position at MS, it is all the more important that I can show my colleagues that ATLAS support and development is a service to the community, and having it at UTSA helps the university and department . . . Thanks, Clint ************************************************************************** ** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley ** ************************************************************************** ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Math-atlas-devel mailing list Math-atlas-devel(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/math-atlas-devel

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Cholesky update/downdate?
by David Warde-Farley Feb. 12, 2010

Feb. 12, 2010

Hi everyone, Does anyone know if there is an implementation of rank 1 updates (and "downdates") to a Cholesky factorization in NumPy or SciPy? It looks there are a bunch of routines for it in LINPACK, but not LAPACK. Thanks, David

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Save the date: SciPy 2010 June 28 - July 3
by Amenity Applewhite Feb. 11, 2010

Feb. 11, 2010

The annual US Scientific Computing with Python Conference, SciPy, has been held at Caltech since it began in 2001. While we always love an excuse to go to California, it’s also important to make sure that we allow everyone an opportunity to attend the conference. So, as Jarrod Millman announced last fall, we’ll begin rotating the conference location and hold the 2010 conference in Austin, Texas. As you may know, Enthought is headquartered in Austin. So in addition to our standard SciPy sponsorship, this year we’ll also be undertaking a great deal of the planning and organization. To begin with, we’re thrilled to announce that we’ve secured several corporate sponsorships that will allow us to host the conference at the brand new AT&T Executive Education and Conference Center on campus at the University of Texas. It’s a wonderful facility in Central Austin and provides easy access to an array of great restaurants, parks, and music venues. We will also be able to provide stipends for our Tutorial presenters for the first time. These community members provide us with an invaluable learning experience every year, and we’re very excited to be able to compensate them for their efforts. And of course, we’ll also continue to offer student sponsorships to support active academic contributors who want to attend the conference. So mark your calendars, folks! June 28 – July 3. Early registration open now. Thanks, The Enthought Team -- Amenity Applewhite Enthought, Inc. Scientific Computing Solutions www.enthought.com

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Determine if two arrays share references
by Keith Goodman Feb. 11, 2010

Feb. 11, 2010

Here are two arrays that share references: >> x = np.array([1,2,3]) >> y = x[1:] and here are two that don't: >> x = np.array([1,2,3]) >> y = x[1:].copy() If I didn't know how the arrays were constructed, how would I determine if any elements in the two arrays share reference? (I'm not sure of my terminology. Please correct me if I'm wrong.)

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Emulate left outer join?
by David Carmean Feb. 11, 2010

Feb. 11, 2010

Hi, I've been working with numpy for less than a month, having learned about it after finding matplotlib. My foundation in things like set theory is... weak to nonexistent, so I need a little help mapping sql-like thoughts into set-theory thinking :) Some context to help me explain: I'm trying to store, chart, and analyze unix system performance data (sar/sadf output). On a typical system I have about 75 fields/variables, all floats, with identical timestamps... or so we hope. What I want to do in order to save memory/disk space is to stack the timeseries data all into three or four different arrays, and use a single timestamp field for each set. My problem is: I don't know that I can guarantee that the shape of all the individual arrays will be identical along the time axis. I may receive truncated textfiles to parse, or new variables may appear and disappear from the set being reported/recorded. If these were in flat files or database tables, I'd do a left outer join between a master timestamp table and each individual variable's table. But... I don't know the keywords to search for in the numpy docs/web chatter. A thread from just about one year ago left the question hanging: http://article.gmane.org/gmane.comp.python.numeric.general/27942 Examples? Pointers? Shoves toward the correct sections of the docs? Thanks.

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loadtxt and genfromtxt
by Jonathan Stickel Feb. 11, 2010

Feb. 11, 2010

I am new to python/numpy/scipy and new to this list. I recently migrated over from using Octave and am very impressed so far! Recently I needed to load data from a text file and quickly found numpy's "loadtxt" function. However, there were missing data values, which loadtxt does not handle. After some amount of googling, I did find "genfromtxt" which does exactly what I need. It would have been helpful if genfromtxt was included in the "See Also" portion of the docstring for loadtxt. Perhaps this is a simple oversight? I see that genfromtxt does mention loadtxt in its docstring. Let me know if I should submit a bug somewhere, or if it is sufficient to mention this small item on the list. Thanks, Jonathan P.S. My first send did not seem to go through. Trying again; sorry if this is posted twice...

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