Mailman 3 May 2006 - NumPy-Discussion

matrix direct sum
by Alan G Isaac 19 May '06

19 May '06

It seems to me that the core question is whether you really need the direct sum to be constructed (seem unlikely), or whether you just need the information in the constituent matrices. How about a direct sum class, which takes a list of matrices as an argument, and appropriately defines the operations you need. Cheers, Alan Isaac PS I have argued that this is a better way to handle the Kronecker product as well, but as here I did not offer code. ;-) If you code it, please share it.

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isdtype
by Fred Clare 19 May '06

19 May '06

None of the functions in section 4.5 of the manual seem to be implemented: >>> import numpy >>> numpy.__version__ '0.9.6' >>> a = numpy.array([0.]) >>> numpy.isdtype(a) Traceback (most recent call last): File "<stdin>", line 1, in ? AttributeError: 'module' object has no attribute 'isdtype' ? Fred Clare

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Numpy Example List
by joris＠ster.kuleuven.ac.be 19 May '06

19 May '06

For your information: http://scipy.org/Numpy_Example_List - all examples are now syntax highlighted (thanks Pau Gargallo!) - most examples have now a clickable "See also:" footnote - is extended to 118 examples Joris Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

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Matrix query
by Satya Upadhya 19 May '06

19 May '06

Dear Python Users and Gurus, My problem is that i have a distance matrix obtained from the software package PHYLIP. I have placed it in a text file, and using ordinary python i am able to save the matrix elements as a multidimensional array. My problem is that i wish to now convert this multidimensional array into a matrix and subsequently i wish to find the eigenvectors and eigenvalues of this matrix. I tried using scipy and also earlier the Numeric and LinearAlgebra modules but i am facing problems. I can generate a new matrix using scipy (and also with Numeric/LinearAlgebra) and can obtain the corresponding eigenvectors. But i am facing a real problem in making scipy or Numeric/LinearAlgebra accept my multidimensional array as a matrix it can recognize. Please help/give a pointer to a similar query. Thanking you, Satya --------------------------------- Do you have a question on a topic you cant find an Answer to. Try Yahoo! Answers India Get the all new Yahoo! Messenger Beta Now

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Indexing arrays with arrays
by Bill Baxter 18 May '06

18 May '06

One thing I haven't quite managed to figure out yet, is what the heck indexing an array with an array is supposed to give you. This is sort of an offshoot of the "nonzero()" discussion. I was wondering why nonzero() and where() return tuples at all instead of just an array, till I tried it. >>> b array([[0, 1, 2], [3, 4, 5], [6, 7, 8]]) >>> b[ num.asarray(num.where(b>4)) ] array([[[3, 4, 5], [6, 7, 8], [6, 7, 8], [6, 7, 8]], [[6, 7, 8], [0, 1, 2], [3, 4, 5], [6, 7, 8]]]) Whoa, not sure what that is. Can someone explain the current rule and in what situations is it useful? Thanks --bb

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NumPy 0.9.8 to be released today
by Travis Oliphant 18 May '06

18 May '06

If there are now further difficulties, I'm going to release 0.9.8 today. Then work on 1.0 can begin. The 1.0 release will consist of a series of release candidates. Thank you to David Cooke for his recent flurry of fixes.. Thanks to all the other developers who have contributed as well. -Travis

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nonzero() behaviour has changed
by Simon Burton 18 May '06

18 May '06

Sometime between 0.9.5 and 0.9.7.2502 the behaviour of nonzero changed: >>> a=numpy.array([1,1,0,1,1]) >>> a.nonzero() array([0, 1, 3, 4]) >>> now it returns a tuple: >>> a=numpy.array((0,1,1,0,0)) >>> a.nonzero() (array([1, 2]),) This is rather unpleasant for me. For example, my collegue uses OSX and finds only numpy 0.9.5 under darwinports. :( Simon. -- Simon Burton, B.Sc. Licensed PO Box 8066 ANU Canberra 2601 Australia Ph. 61 02 6249 6940 http://arrowtheory.com

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Numpy Example List
by joris＠ster.kuleuven.ac.be 18 May '06

18 May '06

Newsflash The Numpy Example List has now passed its 100th example, and has now its own wikipage: http://scipy.org/Numpy_Example_List Thanks to Pau Gargallo for his contributions. Joris Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

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[ANN] EuroPython 2006 - call for papers
by Nicolas Chauvat 18 May '06

18 May '06

Hi Lists, This year again EuroPython will see pythonistas from all over flock together at the same place and the same time : EuroPython 2006 - July, 3rd to 5th - CERN, Geneva, Switzerland Please do not hesitate to submit your presentation proposals to share your insights and experience with all who have an interest in Python put to good use in Science. http://www.europython.org Deadline is May 31st. See you there, -- Nicolas Chauvat logilab.fr - services en informatique avancée et gestion de connaissances

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Re[2]: [Numpy-discussion] nonzero() behaviour has changed
by Alan G Isaac 18 May '06

18 May '06

> Alan G Isaac wrote: >> 1. I hope for an array 'a' that nonzero(a) and a.nonzero() >> will produce the same result, whatever convention is >> chosen. On Wed, 17 May 2006, Travis Oliphant apparently wrote: > Unfortunately this won't work because the nonzero(a) behavior was > inherited from Numeric but the .nonzero() from numarray. > This is the price of trying to merge two user groups. The little bit > of pain is worth it, I think. One last comment: This is definitely trading off surprises for future users against ease for incoming Numeric users. So ... might the best to be to make numpy consistent but, assuming the more consistent numarray behavior is chosen, provide the Numeric behavior as part of the compatability module? fwiw, Alan

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