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[multi_index] Multi-Index as fast running median solver
by Ryan Fogarty 05 Sep '10

05 Sep '10

I'm hoping to use multi-index' ordered_index (non-unique) to do a fast running median. Given a set of M numbers and a window size of N compute the medians (for each of M - N + 1 solutions). Here is my solution: template<typename T> class FastMedianSolver { private: // boost::multi_index does most of the heavy lifting for this FastMedianSolver. // This index is given both "sequence" and "tree" semantics. typedef typename boost::multi_index_container< T,indexed_by<sequenced<>,ordered_non_unique<identity<T> > > > SortedList; typedef typename SortedList::template nth_index<0> SeqIndex; typedef typename SeqIndex::type SIndex; typedef typename SortedList::template nth_index<1> TreeIndex; typedef typename TreeIndex::type TIndex; SortedList mQueue; const size_t mSize; const size_t mHalfSize; public: typedef typename SIndex::iterator iterator; /** * Create a FastMedianSolver with queue size as argument * * @param size - size of the queue. */ // Note: fast divide by 2 is: X >> 1 FastMedianSolver(size_t size) : mSize(size), mHalfSize(size >> 1) {} /** * insert a value into the median queue */ void insert(const T& value) { mQueue.push_front(value); if(mQueue.size() > mSize) mQueue.pop_back(); } /** * Get the median for the elements within the queue. Note: * the algorithm requires a full queue, o.w. may throw an exception. */ const T& getMedian() { // Ensure queue is filled up before we ask for median! assert((mQueue.size() >> 1) == mHalfSize); typename TIndex::iterator tNdx(mQueue.get<1>().begin()); // Now grab the median element // Note that unfortunately the root() node is not exposed so the only way to get the central node // is to iterate to it :( (this will incur a O(N) operation on this function which is a little unfortunate for(int i = 0; i < mHalfSize; ++i,++tNdx); // This would be better if it were available and accurate! // typename TIndex::iterator tNdx(mQueue.get<1>().beginAtRoot()); // TODO: Check if we need to average the output of 2 positions if mSize is even return *tNdx; } }; Note, that to get to the central node I just iterate the ordered list half way through set: for(int i = 0; i < mHalfSize; ++i,++tNdx); However, what I was hoping was that I could get the root node directly. ordered_index doesn't expose an iterator to root() so I put it in ordered_index.hpp as: iterator beginAtRoot(){return make_iterator(root());} However, this isn't working out because the tree isn't always balanced. My question is 2-fold is there any way to force the internal red-black tree to stay balanced; and secondly, would that have an appreciable performance penalty. Thank you, Ryan

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[gsoc] mentor summit
by Andrew Sutton 05 Sep '10

05 Sep '10

If you weren't a mentor for the 2010 Google Summer of Code, you can stop reading now. It looks like the mentor summit will be on October 23-24. If you are interested in attending, now is the time to speak up. Boris Schaeling has already expressed interest in going, and I would also like to attend. Anybody else? Google will only reimburse two trips (up to $2000, I think). If you happen to live in the Mountain View/San Jose area, you could probably just show up (with registration). Andrew Sutton asutton(a)cs.tamu.edu

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[function] invoking without requiring boost::throw_exception
by Peter Myerscough-Jackopson 05 Sep '10

05 Sep '10

Dear all, I am using boost::function on an embedded platform, which requires me to not use exceptions, and as commented in the thread associated with http://article.gmane.org/gmane.comp.lib.boost.devel/195351 I am checking that the function object contains a function before calling it. There is therefore no need for the invocation of the function to check if it is valid, but also there is no method circumvent this checking, and therefore my program requires the definition of boost::throw_exception, when really it is not needed. This is a concern because I intend on compiling my code into a library and do not wish to require the user to define boost::throw_exception, especially when I am guaranteeing it isn't going to be called from this site. I liked the idea of a templated NOP for the function library, but at the very least an unchecked invocation method would be great, or a nop-if-empty invocation method would be useful. A simple addition of the following would assist to some extend : result_type invoke(BOOST_FUNCTION_PARMS) const { return get_vtable()->invoker (this->functor BOOST_FUNCTION_COMMA BOOST_FUNCTION_ARGS); } With maybe a comment next to result_type operator()(BOOST_FUNCTION_PARMS) const; suggesting the use of invoke() when the function is pre-checked, or more importantly you are trying to avoid exception usage. Thanks in advance, and I hope I am not opening a new/old can of worms..... Peter Dr Peter Myerscough-Jackopson - Principal Engineer Tel: +44 (0)23 8076 7808 Fax: +44 (0)23 8076 0602 Web: http://www.macltd.com/ <BLOCKED::http://www.macltd.com/> Email: peter.myerscough-jackopson(a)macltd.com <mailto:peter.myerscough-jackopson@macltd.com> MULTIPLE ACCESS COMMUNICATIONS LIMITED is a company registered in England at Delta House, The University of Southampton Science Park, Southampton, SO16 7NS, United Kingdom with Company Number 1979185 and VAT Number GB 411942866

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[fusion] VC8 specific error
by John Maddock 05 Sep '10

05 Sep '10

I'm getting the following error from fusion only when using VC8: ..\..\..\boost/fusion/sequence/intrinsic/at.hpp(59) : error C2504: 'boost::fusion::extension::at_impl<Tag>::apply<Sequence,N>' : base class undefined with [ Tag=boost::fusion::non_fusion_tag ] and [ Sequence=const boost::tuples::tuple<double,double>, N=boost::mpl::int_<0> ] ..\..\..\boost/fusion/sequence/intrinsic/at.hpp(64) : see reference to class template instantiation 'boost::fusion::result_of::at<Sequence,N>' being compiled with [ Sequence=const boost::tuples::tuple<double,double>, N=boost::mpl::int_<0> ] ..\..\..\boost/math/tools/roots.hpp(47) : see reference to class template instantiation 'boost::fusion::result_of::at_c<Sequence,N>' being compiled with [ Sequence=const boost::tuples::tuple<double,double>, N=0 ] ..\..\..\boost/math/tools/roots.hpp(225) : see reference to function template instantiation 'void boost::math::tools::detail::unpack<boost::tuples::tuple<T0,T1>,T,T>(const Tuple &,T &,U &)' being compiled with [ T0=double, T1=double, T=double, Tuple=boost::tuples::tuple<double,double>, U=double ] compile_test\tools_roots_concept_test.cpp(115) : see reference to function template instantiation 'T boost::math::tools::newton_raphson_iterate<F2t,double>(F,T,T,T,int,boost::uintmax_t &)' being compiled with [ T=double, F=F2t ] The code is simply calling boost::fusion::get<N>() on a fusion tuple, and after including <boost/fusion/tuple.hpp>. Any ideas? This is with Trunk BTW. Cheers, John.

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[NVL++]: new library and utilities
by Manfred Doudar 04 Sep '10

04 Sep '10

Hello List, Have recently released a series of libraries aimed at facilitating computer-vision tasks - taking out much of the boiler-plate associated with connecting to multiple cameras, and image streams generally. Work that is largely the product of almost 1.5 years work, using OpenCV as a back-end, but thread-safe, and all in modern C++, and largely header-file only. For those not particularly interested in computer-vision, there are libraries and miscellaneous utilities that may be of interest, in particular: - a library wrapper over Boost.Thread (not entirely complete, but covers majority of use-cases); and makes threading less error-prone - a library for parsing delimited strings (csv, etc) - a library for parsing command-line options (expresses intent better than Boost.Program_options, betters in some areas, lacks in others) - a library that with a bit more of effort can be made stand-alone for streaming ("chaining") of algorithms, though binders are common-place, some work herein presents alternative approaches. [[Documentation]]: is available, but not of Boost quality, however it is sufficient. Depending upon reaction, what I do with these libraries, depends largely upon feedback I get. [[License]]: largely C++ Boost license, with the exception of a few 3rd-party libs included in the package. [[Platform]]: developed & tested on Linux; compiles with GCC-4.4.2 [[Where to get it]]: for the time being can be found here (until comms at work can get their act together and put up on their open-website) - http://users.cecs.anu.edu.au/~manfredd ..there's only one file there: nvl++.tar.bz2 Cheers, -- Manfred

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Re: [boost] [gil] Who has a big-endian machine?
by Belcourt, Kenneth 03 Sep '10

03 Sep '10

On Sep 1, 2010, at 1:24 PM, Belcourt, Kenneth wrote: > > On Sep 1, 2010, at 12:05 PM, Christian Henning wrote: > >> Hi there, could someone with a big-endian machine run the following >> code with the latest gil code from the trunk? > ./ibm.hw purple.sandia.gov: 31488 MB 8 CPU PowerPC_POWER5 model IBM, 9118-575 > xlC -g -I./boost-trunk gil.cpp > ./a.out Assertion failed: v1 == 6, file gil.cpp, line 47 Abort (core dumped) Same source code. -- Noel

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Towards a Warning free code policy proposal
by vicente.botet 03 Sep '10

03 Sep '10

Hi all, Last year there where two long threads about Boost Warning policy. If I'm not wrong nothing was concluded. I think that we can have two warning policies: one respect to the Boost users and one internal for Boost developement. We can consider that Boost headers can be used by the users as system headers, so no warning is reported for these files. The main advantage I see is that it allows the users to don't mix the warnings comming from Boost and their own warnings. Next follows a way to disable completly warnings for 3 compilers: Any Boost header file could be surrounded by #if defined __GNUC__ #pragma GCC system_header #elif defined __SUNPRO_CC #pragma disable_warn #elif defined _MSC_VER #pragma warning(push, 1) #endif and #if defined __SUNPRO_CC #pragma enable_warn #elif defined _MSC_VER #pragma warning(pop) #endif As we want the developer to be able to catch and eliminate as many warning as possible we need some conditional compilation that allows us to enable the warning reporting internally. These could also be useful for users that prefer to see the Boost warnings. Boost.Exception uses already this policy, sourronding some of its files with #if defined(__GNUC__) && !defined(BOOST_EXCEPTION_ENABLE_WARNINGS) #pragma GCC system_header #endif #if defined(_MSC_VER) && !defined(BOOST_EXCEPTION_ENABLE_WARNINGS) #pragma warning(push,1) #endif and #if defined(_MSC_VER) && !defined(BOOST_EXCEPTION_ENABLE_WARNINGS) #pragma warning(pop) #endif I propose to extend this to a 2-level enabling warning system BOOST_ENABLE_WARNINGS: If defined, enable warnings for all the Boost libraries BOOST_<LIB>_ENABLE_WARNINGS: If defined, enable warnings for a specific library <LIB> Regression testers should run with BOOST_WARNING_ENABLED defined. Developers of a library should run with BOOST_<LIB>_WARNING_ENABLED defined at least. Users could enable warnings at any level just by defining the appropriated macro. With this 2-level enabling policy, the preceding surrounding code becomes: #if !defined(BOOST_ENABLE_WARNINGS) && !defined(BOOST_LIB_ENABLE_WARNINGS) #if defined __GNUC__ #pragma GCC system_header #elif defined __SUNPRO_CC #pragma disable_warn #elif defined _MSC_VER #pragma warning(push, 1) #endif #endif and #if !defined(BOOST_ENABLE_WARNINGS) && !defined(BOOST_LIB_ENABLE_WARNINGS) #if defined __SUNPRO_CC #pragma enable_warn #elif defined _MSC_VER #pragma warning(pop) #endif #endif Due to the nature of the GCC solution, this does not work directly within the source (.cpp) file, only within a header (.hpp) file. So if we want to remove the warnings also from the .cpp files we need to move the code to a .hpp file. // a.cpp #include "warning_free_wrapper/a.hpp" Of course this policy don't mean that the developer should not take care of the warnings. Please, let me know if this policy could satisfy the needs of the Boost users and the developers. Best, _____________________ Vicente Juan Botet Escribá http://viboes.blogspot.com/

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[itl] status?
by Jeff Flinn 03 Sep '10

03 Sep '10

What is the current status of the interval template library? Where can I get the latest version? Thanks, Jeff

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nvcc config and mpl_assert
by Andrey Asadchev 03 Sep '10

03 Sep '10

recent boost distribution introduced nvcc as compiler which results in failed compilation when using mpl assert (and components of mpl which do so) here is the fix (it produces warnings, but allows for compile) --- config/compiler/nvcc.hpp 2010-09-02 18:43:46.000000000 -0500 +++ config/compiler/nvcc.hpp~ 2010-09-02 16:40:32.000000000 -0500 @@ -17,8 +17,8 @@ // Boost support macro for NVCC // NVCC Basically behaves like some flavor of MSVC6 + some specific quirks -//#define BOOST_NO_INCLASS_MEMBER_INITIALIZATION -//#define BOOST_MSVC6_MEMBER_TEMPLATES +#define BOOST_NO_INCLASS_MEMBER_INITIALIZATION +#define BOOST_MSVC6_MEMBER_TEMPLATES #define BOOST_HAS_UNISTD_H #define BOOST_HAS_STDINT_H #define BOOST_HAS_SIGACTION --- mpl/aux_/config/gcc.hpp 2010-09-02 18:49:14.000000000 -0500 +++ mpl/aux_/config/gcc.hpp~ 2010-09-02 19:03:39.000000000 -0500 @@ -14,7 +14,7 @@ // $Date: 2008-10-11 02:19:02 -0400 (Sat, 11 Oct 2008) $ // $Revision: 49267 $ -#if defined(__GNUC__) && !(defined(__EDG_VERSION__) || defined(__CUDACC__)) +#if defined(__GNUC__) && !defined(__EDG_VERSION__) # define BOOST_MPL_CFG_GCC ((__GNUC__ << 8) | __GNUC_MINOR__) #else # define BOOST_MPL_CFG_GCC 0 I think nvcc compiler must be differentiated whenever it uses Microsoft (Windows) or GCC(linux) compiler

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[Locale] MS-LCID's table from MSDN site and Copyrights
by Artyom 03 Sep '10

03 Sep '10

Hello, I need a table for conversion of Windows LCIDs to ISO-639 Language and ISO-3199 Country codes and back. I need this for creation Win32 API based backend for Boost.Locale and ability to convert locale names like en_US to LCID 0x0409. Such table can be found here (link to PDF of this page): <http://msdn.microsoft.com/en-us/library/cc233965.aspx> It contains all I need. Now I want to insert such table to the cpp file and include it to the Boost.Locale library. I've read the Copyright notice on this page but I don't clearly understand: - Can I do this? It seems that this notice allow to copy the data but not sure. - Can I release a file that includes such table under Boost License? I need some advice from people who had already deal with such documents or stuff like this or know to read "lowers language" a little bit better and point me to specific line that would make it clear for me. Thank you Artyom P.S.: I can create a workaround based on iterating over all installed LCID's in runtime and querying their ISO-639 and ISO-3199 codes using GetLocaleInfo first time I need to use such table, but integrating static table would be much simpler and faster solution.

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