Mailman 3 July 2010 - NumPy-Discussion

missing string formatting functionality?
by Neal Becker July 19, 2010

July 19, 2010

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 string. Better still, if np.savestring (returning a string) would implement core functionality, and np.savetxt would just us it.

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Python 2.7 MSI installer for NumPy
by cool-RR July 19, 2010

July 19, 2010

Hello. I'd appreciate if the NumPy team could provide an MSI installer for Python 2.7. Thanks, Ram Rachum.

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numpy 1.5 or 2.0
by Nadav Horesh July 19, 2010

July 19, 2010

What is the difference between these two versions? I usually check out the svn version (now 2.0) and it compiles well with python 2.6, 2.7 and 3.1. Nadav.

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Complex nan ordering
by Pauli Virtanen July 19, 2010

July 19, 2010

Hi, The current way of Numpy handles ordering of complex nan is not very well defined. We should attempt to clarify this for 1.5.0. For example, what should these return: r1 = np.maximum(complex(1, nan), complex(2, 0)) r2 = np.complex64(complex(1, nan)) < np.complex64(complex(2, 0)) or, what should `r3` be after this: r3 = np.array([complex(3, nan), complex(1, 0), complex(nan, 2)]) r3.sort() Previously, we have defined a lexical ordering relation for complex numbers, x < y iff x.real < y.real or (x.real == y.real and x.imag < y.imag) but applying this to the above can cause some surprises: amax([1, 2, 4, complex(3, nan)]) == 4 which breaks nan propagation, and moreover the result depends on the order of the items, and the precise way the algorithm is written. *** Numpy IIRC has specified a lexical order between complex numbers for some time now, unlike Python in which complex numbers are unordered. So we won't change how finite numbers are handled, only the nan handling needs to be specified. *** I suggest the following, aping the way the real nan works: - (z, nan), (nan, z), (nan, nan), where z is any fp value, are all equivalent representations of "cnan", as far as comparisons, sort order, etc are concerned. - The ordering between (z, nan), (nan, z), (nan, nan) is undefined. This means e.g. that maximum([cnan_1, cnan_2]) can return either cnan_1 or cnan_2 if both are some cnans. - Moreover, all comparisons <, >, ==, <=, >= where one or more operands is a cnan are false. - Except that when sorting, cnans are to be placed last. The advantages are now that nan propagation is now easier to implement, and we get faster code. Moreover, complex nans start to behave more similarly as their real counterparts in comparisons etc.; for instance in the above cases r1 = (1, nan) r2 = False r3 = [complex(1, 0), complex(3, nan), complex(nan, 2)] where in `r3` the order of the last two elements is unspecified. This is in fact the SVN trunk now works (final tweaks in r8508, 8509). Comments are welcome. -- Pauli Virtanen

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1.5.x branched
by Pauli Virtanen July 18, 2010

July 18, 2010

Dear all, Based on patches contributed by Christoph Gohlke, I've created a branch for 1.5.x: http://svn.scipy.org/svn/numpy/branches/1.5.x It should be a) Binary compatible with Numpy 1.4 on Python 2.x. This meant rolling back the datetime and a couple other changes. b) Support Python 3.1 and 2.7. I expect it will be easy to track changes in the trunk, even if preparing the release will still take some time. -- Pauli Virtanen

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Caching 2to3 results
by Pauli Virtanen July 18, 2010

July 18, 2010

[shameless plug] For those of you tired of waiting for 2to3 after "rm -rf build": http://github.com/pv/lib2to3cache and cd numpy/ USE_2TO3CACHE=1 python3 setup.py build -- Pauli Virtanen

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rollaxis
by Charles R Harris July 17, 2010

July 17, 2010

So, In [14]: x = zeros((2,3,4)) In [15]: rollaxis(x,0,3).shape Out[15]: (3, 4, 2) In [16]: rollaxis(x,0,2).shape Out[16]: (3, 2, 4) In [17]: rollaxis(x,0,1).shape Out[17]: (2, 3, 4) In [18]: rollaxis(x,0,0).shape Out[18]: (2, 3, 4) How come rollaxis(x,0,0) doesn't move 2 to the end ;) That's what the documentation implies. Chuck

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Numpy svn down
by Charles R Harris July 17, 2010

July 17, 2010

At the moment... Chuck

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PyDocWeb "the doc editor" and github transition
by Vincent Davis July 17, 2010

July 17, 2010

I have not seen anything about the move to github and how this effects pydocweb or did I just miss it. I am willing to adapt pydocweb to work with github but not sure what the desired integration would be. This should not be to difficult but should/needs to be part of the plan and documented. My initial thought is to create a branch for the doc editor. My only thought is to allow the doc editor (and those administering it) to maintain a github repo/branch and then allow those that are in control of the numpy/scipy source to merge/pull the docs with the doc repo/branch. (tell me what to do and I will work on it) Vincent

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Crosstab
by Ionut Sandric July 17, 2010

July 17, 2010

Hi: I have two raster data and I would like to do a crosstabulation between them and export the results to a table in a text file. Is it possible to do it with NumPy? Does someone have an example? T

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