September 2008 - Boost-users

[Min-Max] Usage with a member function as criteria.
by Rodolfo Federico Gamarra 01 Sep '08

01 Sep '08

Hello Boost users, I'm working on my thesis with the Boost library (Boost-1.34.1) running on g++ (GCC) 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2). What I'm trying to do can be done very simply, but I preferred to do it more appropriately, I believe, using the Boost Min-Max library. I'm trying to simultaneously obtain the maximum and minimum values of a member function call over a lists of objects. Suppose there exists a class utl::Particle; with a member function double GetEnergy() const; In a member field of another class I have a list of those particles std::list<utl::Particle> particles; for which I want min/max GetEnergy() values. How is that accomplished using Boost.Min-Max? Below I give some excerpts of some of the things I've tried, but didn't work. In order to try to understand what I was doing I split the code over several lines, so to minimize the non-compiling one. In both cases the error seems to be (that line is what I believe to be the most important part of all the error messages): boost/iterator/iterator_adaptor.hpp:353: error: no match for 'operator-' in... First attempt: boost::function<double(const utl::Particle&)> energy = boost::lambda::bind(&utl::Particle::GetEnergy, boost::lambda::_1 ); boost::transform_iterator< boost::function<double(const utl::Particle&)> , list<utl::Particle>::const_iterator> itBeg(particles.begin(), energy),itEnd(particles.end(), energy); boost::minmax(itBeg, itEnd); // This call doesn't compile. Second attempt: boost::function<double(const utl::Particle&)> energy = boost::lambda::bind(&utl::Particle::GetEnergy, boost::lambda::_1 ); // As in the first case. boost::minmax( boost::make_transform_iterator(particles.begin(),energy ), boost::make_transform_iterator(particles.end() ,energy )); // This call doesn't compile. Thanks a lot for your help. -- Rodolfo Federico Gamarra

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problem with boost io_service
by lakers fan 01 Sep '08

01 Sep '08

Hello, I have an application in which I created an io_service object in the main thread of the application. Then I created a listener object (listener socket class), this class creates a new worker thread and waits for incoming messages. First I created listener socket in the context of the main thread and called async_receive_from() so that io_service has something to work, and then I called io_service.run() in the worker thread. But the run() returned immediately. So I tried creating the socket in the worker thread and called async_receive_from() and then called io_service.run(). Again run() returned immeidately with boost::system::error_code's m_val = 0. Can someone point me in the right direction? i m kind of clueless.. Thanks, Bharani _________________________________________________________________ Talk to your Yahoo! Friends via Windows Live Messenger. Find out how. http://www.windowslive.com/explore/messenger?ocid=TXT_TAGLM_WL_messenger_ya…

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cycle iterator that does keep track of wraparound.
by e r 01 Sep '08

01 Sep '08

hi, regarding http://www.boostpro.com/vault/index.php?action=downloadfile&filename=cycle_… is there an illustration/explanation of the different behaviors of cycle_iterator.hpp and cycle_iterator2.hpp thanks!

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Boost::Thread
by Daryl Haresign 01 Sep '08

01 Sep '08

I've been trying to use boost::thread with a movable structure (see end for code + error). From the online manual ( http://www.boost.org/doc/libs/1_36_0/doc/html/thread/thread_management.html… ) template <class F, class A1, class A2, ...> thread(F f, A1 a1, A2 a2, ...); Preconditions: F and each An must by copyable or movable. Effects: As if thread(boost::bind(f,a1,a2,...)). Consequently, f and each an are copied into internal storage for access by the new thread. I've been running into a problem with this however. The use of boost::bind means that F needs to have a copy constructor, which seems odd as the manual says "or movable". Am I doing something wrong, or is this an oversight, or what? Regards, Daryl. ---------- Code: (built with: gcc version 4.4.0 20080831 (experimental) (GCC) g++-trunk -o move_thread move_thread.cpp --std=c++0x /usr/local/lib/libboost_thread-gcc43-mt.a) ---------- #include <iostream> #include <vector> #include <boost/preprocessor/iteration/iterate.hpp> #include <boost/thread.hpp> using std::cout; using std::endl; using std::vector; using boost::thread; struct S { S(int) { cout << "S()" << endl; } S(S &&) { cout << "S() move" << endl; } void operator()(int i) { cout << "Thread running [" << i << "]" << endl; } S(S const &) = delete; }; int main() { vector<thread> v; for (int i = 0; i < 10; ++i) { v.push_back(thread(S(i), i)); } for (int i = 0; i < 10; ++i) { v[i].join(); } } ---------- Error: ---------- In file included from /usr/local/include/boost/thread/thread.hpp:22, from /usr/local/include/boost/thread.hpp:13, from move_thread.cpp:4: move_thread.cpp: In constructor ‘boost::thread::thread(F, A1) [with F = S, A1 = int]’: move_thread.cpp:26: instantiated from here move_thread.cpp:18: error: deleted function ‘S::S(const S&)’ /usr/local/include/boost/thread/detail/thread.hpp:227: error: used here /usr/local/include/boost/thread/detail/thread.hpp:227: error: initializing argument 2 of ‘boost::_bi::bind_t<R, F, typename boost::_bi::list_av_1<A1>::type> boost::bind(boost::type<R>, F, A1) [with R = void, F = S, A1 = int]’

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[graph] Compressed Sparse Row graph - undirected?
by Mojmir Svoboda 01 Sep '08

01 Sep '08

hello, i am using directed CSR from boost::graph and i have a small problem with memory consumption, as each edge property is duplicated. i can of course make edge property to be some index and reduce this, but i have an editor part of graph that is adjacency_list and i'd like the properties to be the same. my primary question is: is there a way to implement an undirected csr graph? anyway, when constructing directed graph from undirected there is a slight bug in implementation, because it allocates space for only N edges(properties) instead of 2N. or am i missing something? another thing: perhaps i am doing something wrong, but this code seems to go 'one field beyond' the allocated space. can you confirm, please? edge_iterator& operator++() { ++current_edge.idx; while (current_edge.idx == end_of_this_vertex) { ++current_edge.src; end_of_this_vertex = rowstart_array[current_edge.src + 1]; ^^^^^^^^^^^^^^^^^^^^ } return *this; } many thanks for your attention, mojmir

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[review] Dataflow Review starts today, September 1st
by jarvi＠cs.tamu.edu 01 Sep '08

01 Sep '08

The review of Stjepan Rajko's Dataflow library starts today, September 1st, and will run until September 10th. --------------------------------------------------------- Description of the library: Dataflow is a generic library for dataflow programming. Dataflow programs can typically be expressed as a graph in which vertices represent components that process data, and edges represent the flow of data between the components. As such, dataflow programs can be easily reconfigured by changing the components and/or the connections. This review focuses on the Dataflow.Signals layer of the library. For its data transport mechanism, Dataflow.Signals uses Boost.Signals which can be used to make lasting dataflow connections based on function calls. Dataflow.Signals provides the following to facilitate signals-based dataflow networks: * A number of useful general-purpose components, and building blocks for implementing new components. * Various free functions and operators for connecting and using components. The library documentation provides some concrete examples of how Dataflow.Signals layer can be used. Some examples are: * Implementing distributed dataflow applications using Dataflow.Signals and Boost.Asio * An image processing network using Dataflow.Signals and Boost.GIL * A GUI dataflow editor (located in the Dataflow.Blueprint documentation) While the Dataflow library contains other layers, only the Dataflow.Signals layer is ready for review. Reviewers are welcome to provide feedback for any part of the library, but please be aware that the documentation and implementation for the other layers may be lacking (for example, there is the generic support layer, which provides concepts applicable to different dataflow frameworks, and can be used to develop generic dataflow code, as well as the Dataflow.Blueprint layer which provides run-time reflection and modeling of dataflow networks in a Boost Graph Library graph for any dataflow framework with implemented Dataflow library support). For the time being, please consider these other layers as implementation details or proof-of-concept examples, as appropriate. The library is accessible as a tarball at: http://www.boostpro.com/vault/index.php?&directory=Dataflow The documentation can be accessed here: http://www.dancinghacker.com/code/dataflow/ The documentation particular to the Dataflow.Signals layer under review: http://www.dancinghacker.com/code/dataflow/dataflow/signals.html Dataflow depends on many existing Boost libraries, such as Fusion and MPL. The Dataflow.Signals layer builds functionality over Boost.Signals. The Dataflow library has been tested using a recent version of the Boost trunk, as well as the 1.35 release. Tests and examples have been built successfuly on OS X (GCC 4.0, 4.2), Linux (GCC 4.2), and Windows (MSVC 8.0 and to some degree MinGW GCC 4.2). --------------------------------------------------------- --------------------------------------------------------- Questions you may want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? In particular, please remember to answer the following question explicitly: - Do you think the library should be accepted as a Boost library? Jaakko Järvi Review Manager

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Re: [Boost-users] RE Outer product in the uBLAS
by Ting Yu 01 Sep '08

01 Sep '08

Thanks Bron for your reply. I am quit sure it is about the outer product. The ordinary product is also named as inner product, which indeed works in an opposite way. The outer product is used very rarely, but this time it happens to me. I have tried the "prod", and it only work as an inner product. Cheers Ting Yu At 04:18 PM 1/09/2008, you wrote: >maybe you just want "prod"? > >F. Bron >___________________________________ > >boost-users-bounces(a)lists.boost.org a écrit sur 01/09/2008 03:56:15 : > > > Hi All, > > I am using the uBLAS to do an outer product between a vector and a > > matrix. The function "outer_prod" seems to only accept two vectors > > instead of a vector and a matrix. Is there anyone successfully to do > > the outer product between a vector and a matrix? Many Thanks > > > > Cheers > > > > Ting Yu > > > > Research Fellow, PhD > > The Center for Integrated Sustainability Analysis (ISA) > > Office: Room 408, Physics Building A28, University of Sydney, NSW 2006 > > Tel: (02) 9351 2627 (Shared) > > Fax: (02) 9351 7726 > > > > > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > >Avis : >Ce message et toute pièce jointe sont la >propriété d'Alcan et sont destinés seulement aux >personnes ou à l'entité à qui le message est >adressé. Si vous avez reçu ce message par erreur, veuillez le >détruire et en aviser l'expéditeur par courriel. >Si vous n'êtes pas le destinataire du message, >vous n'êtes pas autorisé à utiliser, à copier ou >à divulguer le contenu du message ou ses pièces jointes >en tout ou en partie. > >Notice: >This message and any attachments are the >property of Alcan and are intended solely for >the named recipients or entity to whom this >message is addressed. If you have received this message in error >please inform the sender via e-mail and destroy >the message. If you are not the intended >recipient you are not allowed to use, copy or >disclose the contents or attachments in whole or in part. > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users Research Fellow, PhD The Center for Integrated Sustainability Analysis (ISA) Office: Room 408, Physics Building A28, University of Sydney, NSW 2006 Tel: (02) 9351 2627 (Shared) Fax: (02) 9351 7726 Web: http://www.physics.usyd.edu.au/~tingyu/

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Outer product in the uBLAS
by Ting Yu 01 Sep '08

01 Sep '08

Hi All, I am using the uBLAS to do an outer product between a vector and a matrix. The function "outer_prod" seems to only accept two vectors instead of a vector and a matrix. Is there anyone successfully to do the outer product between a vector and a matrix? Many Thanks Cheers Ting Yu Research Fellow, PhD The Center for Integrated Sustainability Analysis (ISA) Office: Room 408, Physics Building A28, University of Sydney, NSW 2006 Tel: (02) 9351 2627 (Shared) Fax: (02) 9351 7726

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