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    Raymond Ehlers
    @raymondEhlers
    @jpivarski Thanks for sharing! That's about what I would have guessed. I've tried to encourage python, but with only some success :-)
    Luke Kreczko
    @kreczko
    @raymondEhlers "Python is slow", huh? ;)
    Martin Ritter
    @daritter
    @jpivarski I would not dare to judge how the distribution is in Belle2. I can say we only teach python (pandas,mpl) for beginners but there's a large fraction of people coming over from Belle and they have a very high inertia and prefer to use "ROOT macros". However I can tell you that any Belle2 member that would put their analysis on github/gitlab would be definitely the ones using python for analysis so I'd expect a heavy bias there.
    Hans Dembinski
    @HDembinski
    @jpivarski Thank you for this awesome analysis. According to the voluntary survey 2018 that I conducted within the LHCb collaboration, half of the LHCb members use mainly Python. It is similar to your CMS results.
    Hard data (even with caveats, perhaps Python users prefer Github??) such as yours is even more convincing than personal statements
    Jim Pivarski
    @jpivarski
    @HDembinski Could you point me to that survey?
    I am trying to dig up the URL of the actual poll now...
    Some of the free-form text answers are quite interesting :)
    Matthew Feickert
    @matthewfeickert

    @HDembinski As I've been trying to figure out the issues that pyhf is having with iminuit this weekend I've run into a problem where installing iminuit in a Unbuntu 18.04 Docker image with Python 3.6.8 installed from source on it fails. I have a short Gist that describes what's going on, and if you have any thoughts on what to think about with regards to what is going wrong that would be great:

    https://gist.github.com/matthewfeickert/284cbddc4a60aca2dcda29c354189b35

    Martin Ritter
    @daritter
    @matthewfeickert sounds like the so would have been compiled with gcc instead of g++. Your install_python.sh passes gcc as with-cxx-main, maybe that should be g++?
    Matthew Feickert
    @matthewfeickert
    @daritter Thanks for the quick reply. That's a very interesting point. Let me flip that and see how things go (I'll report back morning CST time). Thanks!
    Matthew Feickert
    @matthewfeickert
    @daritter Actually, just tried swapping out my CXX_VERSION="$(which gcc)" for CXX_VERSION="$(which g++)" and tried to rebuild the Docker image, but this just results in CPython complaining loudly and then failing during the build. So unless I'm doing something stupid I guess that needs to be gcc.
    Martin Ritter
    @daritter
    Then I have no clear idea. I usually don't specify with-cxx-main flag. What does your sysconfig.get_config_var('CXX') and LDCXXSHARED say?
    Henry Schreiner
    @henryiii
    From what I understand here, this will also be picked up from CXX if not given, so it really seems like it should be g++. Never tried passing it explicitly either.
    Henry Schreiner
    @henryiii
    Looks like the problem is a bug in Python: https://bugs.python.org/issue23644 - it seems to be trying to build with stdatomic, which is C++ only.
    Matthew Feickert
    @matthewfeickert

    From the looks of it @henryiii's and @daritter 's suggestion of removing the with-cxx-main flag seems to do the trick. I rebuilt and was able to build through iminuit in the container. :+1: I'll need to do some experimentation with the configure options, but I found the following from the old SVN Python 2.7 trunk very helpful

    --with-cxx-main=<compiler>: If you plan to use C++ extension modules, then -- on some platforms -- you need to compile python's main() function with the C++ compiler. With this option, make will use <compiler> to compile main() and to link the python executable. It is likely that the resulting executable depends on the C++ runtime library of <compiler>. (The default is --without-cxx-main.)

    There are platforms that do not require you to build Python with a C++ compiler in order to use C++ extension modules. E.g., x86 Linux with ELF shared binaries and GCC 3.x, 4.x is such a platform. We recommend that you configure Python --without-cxx-main on those platforms because a mismatch between the C++ compiler version used to build Python and to build a C++ extension module is likely to cause a crash at runtime.

    The Python installation also stores the variable CXX that determines, e.g., the C++ compiler distutils calls by default to build C++ extensions. If you set CXX on the configure command line to any string of non-zero length, then configure won't change CXX. If you do not preset CXX but pass --with-cxx-main=<compiler>, then configure sets CXX=<compiler>. In all other cases, configure looks for a C++ compiler by some common names (c++, g++, gcc, CC, cxx, cc++, cl) and sets CXX to the first compiler it finds. If it does not find any C++ compiler, then it sets CXX="".

    Similarly, if you want to change the command used to link the python executable, then set LINKCC on the configure command line.

    Kinda unfortunate that I can't find that level of detail in modern Python, but maybe I'm not searching hard enough through CPython's GitHub

    Matthew Feickert
    @matthewfeickert

    @henryiii This information on https://bugs.python.org/issue23644 is also very nice. Thanks for taking the time to go find it!

    I don't think that CPython can be built by g++. - STINNER Victor

    This was exactly why I originally had it set to which gcc, but it seems that not explicitly setting compiler flags is the way to go.

    Matthew Feickert
    @matthewfeickert

    @daritter @henryiii Thanks to your help the problem is now resolved: matthewfeickert/Docker-Python3-Ubuntu#3

    @HDembinski Please ignore my ping as the issue no longer exists.

    Henry Schreiner
    @henryiii
    I have just released a series of posts over Azure DevOps, ending with a tutorial on building wheels for a non-trivial binary package (boost-histogram). Start here if you are interested!
    Matthew Feickert
    @matthewfeickert
    These look beautifully written @henryiii!
    Patrick Bos
    @egpbos
    impressive posts @henryiii!
    benkrikler
    @benkrikler
    @henryiii I tried setting up Azure CI with github for a project a few days ago and looked at your work in scikit-hep/particle for some guidance. I couldn't get llvmlite to install for linux and Python2 however, have you faced this issue at all?
    Henry Schreiner
    @henryiii
    I haven’t tried (I guess this is for Numba?), but llvmlight does at least has a manylinux1 python2.7 wheel, so I would have expected it to download that and “Just Work”. What problem were you seeing?
    benkrikler
    @benkrikler
    Yes, thats right, it was for Numba. I was installing that from pip, but I didn't try conda, actually; I suppose that would be more reliable. In the default linux agent it was only finding LLVM 3.8, but llvmlite requires 7.0 or greater.
    Henry Schreiner
    @henryiii
    The easiest way would be to add a container image and use docker - should be a one line addition. I'll check a pip installer later. Python 3 worked, I guess from your comment?
    Contrary to what you might expect, llvmlite does not use any LLVM shared libraries that may be present on the system, or in the conda environment. The parts of LLVM required by llvmlite are statically linked at build time. As a result, installing llvmlite from a binary package does not also require the end user to install LLVM. (For more details on the reasoning behind this, see: Why Static Linking to LLVM?)
    Henry Schreiner
    @henryiii
    That's for pip too. So don't know why it would try to build, and it it didn't, it should not care what version of LLVM is present.
    benkrikler
    @benkrikler
    I tried using a centos7 image as well but it gave me some other headache, which I've now forgotten. It worked fine for python3, only for python2 was it an issue, which also seemed strange to me.
    Hans Dembinski
    @HDembinski
    @matthewfeickert Sorry for not responding sooner. I am currently on holidays, but it seems that your problem was resolved, thanks everyone who jumped in!
    Tai Sakuma
    @TaiSakuma
    how can you tell which Python versions are supported by each coda-forge package?
    Henry Schreiner
    @henryiii
    Conda forge always supports 2.7, 3.6, and 3.7, unless a package turns one off. You can always check anaconda.org to see what files are listed, like: https://anaconda.org/conda-forge/root/files (Very similar to the way I checked for Python 2.7 wheels on PyPI above)
    Tai Sakuma
    @TaiSakuma
    i see. thank you
    Jonas Eschle
    @jonas-eschle
    You can also use conda search package_name (plus some selection if you like, see options) to list the package and it's builds. There you see which version is available for which Python version (mostly)
    e.g. to find keras in conda-forge, do conda search keras[channel=conda-forge]
    Tai Sakuma
    @TaiSakuma
    ok. thank you
    Charles Escott
    @EscottC
    Hi
    Jim Pivarski
    @jpivarski
    @EscottC Hi!
    Tai Sakuma
    @TaiSakuma
    Hi
    Tai Sakuma
    @TaiSakuma
    how would you midify __repr__ of a function? would you do this?
    Jonas Eschle
    @jonas-eschle
    This seems the way to go, since repr is implemented as type(func).__repr__(func) with func being your function. Therefore, some kind of wrapping is necessary. Either with a function wrapper as desribed in your link or, depending on your context you may even need to change more, by creating a class instead of a function and implement the __call__.
    Tai Sakuma
    @TaiSakuma
    Thanks. I have been trying. repr() works. But the problem is the decorated function is not picklable.
    Jonas Eschle
    @jonas-eschle

    Did you use the functools.wraps? Should be used anyway for any wrapping, like:

    def decorator(func):
        @functools.wraps(func)
        def new_func():
            print(f"Wrapped {func}")
        return new_func

    the problem arises from name clash, e.g. your wrapped function has the same name as the unwrapped. functools.wraps solves that. Explanation e.g. here

    Tai Sakuma
    @TaiSakuma
    Yes. That is what I have been trying. I'm not sure where to put wraps.
    The example wraps a function with another function. I need to wrap a functiona with a class (with __call__()).
    Henry Schreiner
    @henryiii
    This should get you pretty close, but does not copy the signature; you’ll need something more powerful for that, like wrapt or decorator.
    In [11]: def nice_repr(func):
        ...:     class NiceFunction:
        ...:         def __repr__(self):
        ...:             return f"Nice repr function of {func.__name__}"
        ...:         @functools.wraps(func)
        ...:         def __call__(self, *args, **kargs):
        ...:             return func(*args, **kargs)
        ...:     return NiceFunction()
    
    In [17]: @nice_repr
        ...: def f(x: float):
        ...:     'Squares a float'
        ...:     return x**2
    
    In [18]: f
    Out[18]: Nice repr function of f
    
    In [19]: f(2)
    Out[19]: 4
    
    In [20]: f?
    Signature:      f()
    Type:           NiceFunction
    String form:    Nice repr function of f
    Docstring:      <no docstring>
    Call docstring: Squares a float
    Tai Sakuma
    @TaiSakuma
    Thank you.
    I cannot pickle f
    I get AttributeError: Can't pickle local object 'nice_repr.<locals>.NiceFunction'